[DOC] Improve formatting in Markdown files (#12322)

* Fix WASM bullet/code indentation

* Use `console` code highlighting where appropriate

… which handles the prefix `$` correctly.

* Migrate feature proposal template to MarkDown

* Set language on code blocks

2 files changed, 37 insertions, 36 deletions

diff --git a/doc/ruby/option_dump.md b/doc/ruby/option_dump.md
index 00d0ec77d5..5324c335d0 100644
--- a/doc/ruby/option_dump.md
+++ b/doc/ruby/option_dump.md
@@ -5,7 +5,7 @@ see {Option --dump}[options_md.html#label--dump-3A+Dump+Items].
 
 For the examples here, we use this program:
 
-```sh
+```console
 $ cat t.rb
 puts 'Foo'
 ```
@@ -26,7 +26,7 @@ The supported dump items:
 - `parsetree`: {Abstract syntax tree}[https://en.wikipedia.org/wiki/Abstract_syntax_tree]
   (AST):
 
-    ```sh
+    ```console
     $ ruby --dump=parsetree t.rb
     ###########################################################
     ## Do NOT use this node dump for any purpose other than  ##
@@ -52,7 +52,7 @@ The supported dump items:
 
 - `parsetree_with_comment`: AST with comments:
 
-    ```sh
+    ```console
     $ ruby --dump=parsetree_with_comment t.rb
     ###########################################################
     ## Do NOT use this node dump for any purpose other than  ##
@@ -89,7 +89,7 @@ The supported dump items:
 
 - `yydebug`: Debugging information from yacc parser generator:
 
-    ```sh
+    ```
     $ ruby --dump=yydebug t.rb
     Starting parse
     Entering state 0
diff --git a/doc/ruby/options.md b/doc/ruby/options.md
index 143c8925f1..6e0278e143 100644
--- a/doc/ruby/options.md
+++ b/doc/ruby/options.md
@@ -5,13 +5,13 @@
 Some examples here use command-line option `-e`,
 which passes the Ruby code to be executed on the command line itself:
 
-```sh
+```console
 $ ruby -e 'puts "Hello, World."'
 ```
 
 Some examples here assume that file `desiderata.txt` exists:
 
-```
+```console
 $ cat desiderata.txt
 Go placidly amid the noise and the haste,
 and remember what peace there may be in silence.
@@ -44,7 +44,7 @@ argument values:
 
 Examples:
 
-```sh
+```console
 $ ruby -0 -e 'p $/'
 "\x00"
 ruby -00 -e 'p $/'
@@ -77,7 +77,7 @@ See also:
 Option `-a`, when given with either of options `-n` or `-p`,
 splits the string at `$_` into an array of strings at `$F`:
 
-```sh
+```console
 $ ruby -an -e 'p $F' desiderata.txt
 ["Go", "placidly", "amid", "the", "noise", "and", "the", "haste,"]
 ["and", "remember", "what", "peace", "there", "may", "be", "in", "silence."]
@@ -107,7 +107,7 @@ See also:
 Option `-c` specifies that the specified Ruby program
 should be checked for syntax, but not actually executed:
 
-```
+```console
 $ ruby -e 'puts "Foo"'
 Foo
 $ ruby -c -e 'puts "Foo"'
@@ -120,7 +120,7 @@ The argument to option `-C` specifies a working directory
 for the invoked Ruby program;
 does not change the working directory for the current process:
 
-```sh
+```console
 $ basename `pwd`
 ruby
 $ ruby -C lib -e 'puts File.basename(Dir.pwd)'
@@ -140,7 +140,7 @@ these commonly write to `$stdout` or `$stderr`.
 The default value for `$DEBUG` is `false`;
 option `-d` sets it to `true`:
 
-```sh
+```console
 $ ruby -e 'p $DEBUG'
 false
 $ ruby -d -e 'p $DEBUG'
@@ -154,7 +154,7 @@ Option `--debug` is an alias for option `-d`.
 Option `-e` requires an argument, which is Ruby code to be executed;
 the option may be given more than once:
 
-```
+```console
 $ ruby -e 'puts "Foo"' -e 'puts "Bar"'
 Foo
 Bar
@@ -170,7 +170,7 @@ but should not include arguments (which, if given, are ignored).
 Option `-E` requires an argument, which specifies either the default external encoding,
 or both the default external and internal encodings for the invoked Ruby program:
 
-```
+```console
 # No option -E.
 $ ruby -e 'p [Encoding::default_external, Encoding::default_internal]'
 [#<Encoding:UTF-8>, nil]
@@ -198,7 +198,7 @@ Option `--encoding` is an alias for option `-E`.
 Option `-F`, when given with option `-a`,
 specifies that its argument is to be the input field separator to be used for splitting:
 
-```sh
+```console
 $ ruby -an -Fs -e 'p $F' desiderata.txt
 ["Go placidly amid the noi", "e and the ha", "te,\n"]
 ["and remember what peace there may be in ", "ilence.\n"]
@@ -208,7 +208,7 @@ $ ruby -an -Fs -e 'p $F' desiderata.txt
 
 The argument may be a regular expression:
 
-```
+```console
 $ ruby -an -F'[.,]\s*' -e 'p $F' desiderata.txt
 ["Go placidly amid the noise and the haste"]
 ["and remember what peace there may be in silence"]
@@ -247,7 +247,7 @@ For a longer help message, use option `--help`.
 Option `-i` sets the \ARGF in-place mode for the invoked Ruby program;
 see ARGF#inplace_mode=:
 
-```
+```console
 $ ruby -e 'p ARGF.inplace_mode'
 nil
 $ ruby -i -e 'p ARGF.inplace_mode'
@@ -262,7 +262,7 @@ The argument to option `-I` specifies a directory
 to be added to the array in global variable `$LOAD_PATH`;
 the option may be given more than once:
 
-```sh
+```console
 $ pushd /tmp
 $ ruby -e 'p $LOAD_PATH.size'
 8
@@ -287,7 +287,7 @@ modifies line-ending processing by:
 
 Without option `-l` (unchopped):
 
-```sh
+```console
 $ ruby -n -e 'p $_' desiderata.txt
 "Go placidly amid the noise and the haste,\n"
 "and remember what peace there may be in silence.\n"
@@ -297,7 +297,7 @@ $ ruby -n -e 'p $_' desiderata.txt
 
 With option `-l' (chopped):
 
-```sh
+```console
 $ ruby -ln -e 'p $_' desiderata.txt
 "Go placidly amid the noise and the haste,"
 "and remember what peace there may be in silence."
@@ -320,9 +320,9 @@ See also:
 
 ### `-n`: Run Program in `gets` Loop
 
-Option `-n` runs your program in a Kernel#gets loop:
+Option `-n` runs your program in a `Kernel#gets` loop:
 
-```
+```ruby
 while gets
   # Your Ruby code.
 end
@@ -331,7 +331,7 @@ end
 Note that `gets` reads the next line and sets global variable `$_`
 to the last read line:
 
-```sh
+```console
 $ ruby -n -e 'puts $_' desiderata.txt
 Go placidly amid the noise and the haste,
 and remember what peace there may be in silence.
@@ -356,7 +356,7 @@ See also:
 
 Option `-p` is like option `-n`, but also prints each line:
 
-```sh
+```console
 $ ruby -p -e 'puts $_.size' desiderata.txt
 42
 Go placidly amid the noise and the haste,
@@ -387,7 +387,7 @@ The argument to option `-r` specifies a library to be required
 before executing the Ruby program;
 the option may be given more than once:
 
-```sh
+```console
 $ ruby -e 'p defined?(JSON); p defined?(CSV)'
 nil
 nil
@@ -413,7 +413,7 @@ in the invoked Ruby program:
 
 More than one custom option may be given:
 
-```
+```console
 $ cat t.rb
 p [$foo, $bar]
 $ ruby t.rb
@@ -439,7 +439,7 @@ the program is executed in the shell's current working directory
 
 This example uses adds path `'tmp/'` to the `PATH` environment variable:
 
-```sh
+```console
 $ export PATH=/tmp:$PATH
 $ echo "puts File.basename(Dir.pwd)" > /tmp/t.rb
 $ ruby -S t.rb
@@ -450,7 +450,7 @@ ruby
 
 Options `-v` prints the Ruby version and sets global variable `$VERBOSE`:
 
-```
+```console
 $ ruby -e 'p $VERBOSE'
 false
 $ ruby -v -e 'p $VERBOSE'
@@ -482,7 +482,7 @@ by setting the initial value of global variable `$-W`:
 The value of `$-W`, in turn, determines which warning messages (if any)
 are to be printed to `$stdout` (see Kernel#warn):
 
-```sh
+```console
 $ ruby -W1 -e 'p $foo'
 nil
 $ ruby -W2 -e 'p $foo'
@@ -493,14 +493,15 @@ nil
 Ruby code may also define warnings for certain categories;
 these are the default settings for the defined categories:
 
-```
+```rb
 Warning[:experimental] # => true
 Warning[:deprecated]   # => false
 Warning[:performance]  # => false
 ```
 
 They may also be set:
-```
+
+```rb
 Warning[:experimental] = false
 Warning[:deprecated]   = true
 Warning[:performance]  = true
@@ -508,7 +509,7 @@ Warning[:performance]  = true
 
 You can suppress a category by prefixing `no-` to the category name:
 
-```
+```console
 $ ruby -W:no-experimental -e 'p IO::Buffer.new'
 #<IO::Buffer>
 ```
@@ -529,7 +530,7 @@ The ruby code:
 
 Example:
 
-```sh
+```console
 $ cat t.txt
 Leading garbage.
 #!ruby
@@ -545,7 +546,7 @@ The optional argument specifies the directory where the text file
 is to be found;
 the Ruby code is executed in that directory:
 
-```sh
+```console
 $ cp t.txt /tmp/
 $ ruby -x/tmp t.txt
 tmp
@@ -567,7 +568,7 @@ See Thread::Backtrace.limit.
 
 Option `--copyright` prints a copyright message:
 
-```sh
+```console
 $ ruby --copyright
 ruby - Copyright (C) 1993-2024 Yukihiro Matsumoto
 ```
@@ -642,7 +643,7 @@ sets the default external encoding for the invoked Ruby program;
 for values of +encoding+,
 see {Encoding: Names and Aliases}[rdoc-ref:encodings.rdoc@Names+and+Aliases].
 
-```sh
+```console
 $ ruby -e 'puts Encoding::default_external'
 UTF-8
 $ ruby --external-encoding=cesu-8 -e 'puts Encoding::default_external'
@@ -664,7 +665,7 @@ sets the default internal encoding for the invoked Ruby program;
 for values of +encoding+,
 see {Encoding: Names and Aliases}[rdoc-ref:encodings.rdoc@Names+and+Aliases].
 
-```sh
+```console
 $ ruby -e 'puts Encoding::default_internal.nil?'
 true
 $ ruby --internal-encoding=cesu-8 -e 'puts Encoding::default_internal'