(https://github.com/ruby/rdoc/pull/1240)

Some people like to mark up method names in MarkDown style block
quotes, like this: ruby/ruby#12333.
Currently, no links are created in the code in the RDoc, but such
words most likely refer to methods.
This PR makes a word a code cross-reference if the whole word can be
resolved as a reference.

https://github.com/ruby/rdoc/commit/7d7efb0709

(https://github.com/ruby/rdoc/pull/1247)

https://github.com/ruby/rdoc/commit/cbbf04d6f8

(https://github.com/ruby/rdoc/pull/1241)

https://github.com/ruby/rdoc/commit/4a5206ae56

(https://github.com/ruby/rdoc/pull/1209)

* Use the original `label` description list style

As a default for all description lists, the original "label" style is
more readable.

This is slightly different from the original `label` dl though:
* slightly increased left margin for `dd` (to 1em)
* removed right margin on `dd`
* removed `dt` bottom margin and `dd` top margin, to reduce the gap
  between the term and its description (to only the standard line-height
  gap).

* Add closing tags for description list terms

Without the closing tags, the dt elements contain whitespace after the
text.  This normally isn't a big deal, but does mess some things up,
e.g: using `::after` with `content: ", "` in stylesheets.

* Restore float:left style for note lists

Unlike the original note list styles, this version sets the line-height
for all `dt` elements to be the same as the `p` elements contained
inside the `dd`, so that the second line has the same indentation as all
subsequent lines.

* Add commas between note list terms

https://github.com/ruby/rdoc/commit/9e69ea6d75

(https://github.com/ruby/rdoc/pull/1218)

* Deprecate :main: directive

* Deprecate :title: direcive

* Update documentation

* Remove :main: directive's usage

* Update test cases

* Add '.rdoc_options' to suggested alternatives

https://github.com/ruby/rdoc/commit/e2d4ac9dad

(https://github.com/ruby/rdoc/pull/1184)

https://github.com/ruby/rdoc/commit/7b68545094

(https://github.com/ruby/rdoc/pull/1144)

* Add a new ruby parser RDoc::Parser::PrismRuby

* Add a new ruby parser testcase independent from parser's internal implementation

* unknown meta method

* Use MethodSignatureVisitor only to scan params, block_params and calls_super

* Add calls_super test

* Drop ruby 2.6. Prism requires ruby >= 2.7

* Remove duplicated documentation comment from prism_ruby.rb

* Add test for wrong argument passed to metaprogramming method

* Rename visit_call_[DSL_METHOD_NAME] to make it distinguishable from visit_[NODE_TYPE]_node

* Method receiver switch of true/false/nil to a case statement

* Extract common part of add_method(by def keyword) and add meta_comment method

* Reuse consecutive comments array when collecting comments

* Simplify DSL call_node handling

* Refactor extracting method visibility arguments

https://github.com/ruby/rdoc/commit/fde99f1be6

(https://github.com/ruby/rdoc/pull/1139)

* Rename rake rubocop to rake format_generated_files

* Add rubocop rules to ensure spaces are applied consistently

* Improve rubocop related CI workflows

https://github.com/ruby/rdoc/commit/27932d001c

Previously, trying to round-trip label-list and name-lists with the
ToRdoc converter was not possible:

```ruby
doc = <<~RDOC
foo ::
bar ::
  hi
RDOC

markup = RDoc::Markup.parse(doc)
markup # => [doc: [list: NOTE [item: ["foo ", "bar"]; [para: "hi"]]]]

rt = RDoc::Markup::ToRdoc.new.convert(markup)
rt # => "foo\nbar:\n  hi\n\n"

rt_markup = RDoc::Markup.parse(rt)
rt_markup # => [doc: [para: "foo ", "bar:"], [verb: "hi\n"]]
```

This commit addresses the issue by fixing ToRdoc to generate output that
can be properly reparsed by RDoc. ToRdoc tests additionally needed to be
updated for the new output.

The old implementation of `accept_list_item_start` was copied to ToBs
because those tests did not pass with the new changes and I am
unfamiliar with the `backspace` format.

After:

```ruby
doc = <<~RDOC
foo ::
bar ::
  hi
RDOC

markup = RDoc::Markup.parse(doc)
markup # => [doc: [list: NOTE [item: ["foo ", "bar"]; [para: "hi"]]]]

rt = RDoc::Markup::ToRdoc.new.convert(markup)
rt # => "foo::\nbar::\n  hi\n\n"

rt_markup = RDoc::Markup.parse(rt)
rt_markup # => [doc: [list: NOTE [item: ["foo", "bar"]; [para: "hi"], blankline]]]
```

https://github.com/ruby/rdoc/commit/c6c51aa900