[DOC] Resurrected YJIT section

under "Implementation improvements", similarly to past versions.

We also don't do categorization like "* New features" (which was in this
file) or "New features:" (which was on the release notes), so I used the
standard header format instead.

I applied the same change to release notes, copied the same thing back
to NEWS.md, and then removed the TL;DR section from it.

1 files changed, 28 insertions, 24 deletions

diff --git a/NEWS.md b/NEWS.md
index 1ab6e42ad6..138ea591fc 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -448,30 +448,34 @@ The following bundled gems are promoted from default gems.
   enabled using the environment variable `RUBY_GC_LIBRARY=mmtk`. This requires
   the Rust toolchain on the build machine. [[Feature #20860]]
 
-* New features of YJIT
-  * Add unified memory limit via `--yjit-mem-size` command-line option (default 128MiB)
-    which tracks total YJIT memory usage and is more intuitive than the
-    old `--yjit-exec-mem-size`.
-  * More statistics now always available via `RubyVM::YJIT.runtime_stats`
-  * Add compilation log to track what gets compiled via `--yjit-log`
-    * Tail of the log also available at run-time via `RubyVM::YJIT.log`
-  * Add support for shareable consts in multi-ractor mode
-  * Can now trace counted exits with `--yjit-trace-exits=COUNTER`
-  * Compressed context reduces memory needed to store YJIT metadata
-
-* New optimizations of YJIT
-  * Improved allocator with ability to allocate registers for local variables
-  * When YJIT is enabled, use more Core primitives written in Ruby:
-    * `Array#each`, `Array#select`, `Array#map` rewritten in Ruby for better performance [[Feature #20182]].
-  * Ability to inline small/trivial methods such as:
-    * Empty methods
-    * Methods returning a constant
-    * Methods returning `self`
-    * Methods directly returning an argument
-  * Specialized codegen for many more runtime methods
-  * Optimize `String#getbyte`, `String#setbyte` and other string methods
-  * Optimize bitwise operations to speed up low-level bit/byte manipulation
-  * Various other incremental optimizations
+### YJIT
+
+#### New features
+
+* Add unified memory limit via `--yjit-mem-size` command-line option (default 128MiB)
+  which tracks total YJIT memory usage and is more intuitive than the
+  old `--yjit-exec-mem-size`.
+* More statistics now always available via `RubyVM::YJIT.runtime_stats`
+* Add compilation log to track what gets compiled via `--yjit-log`
+  * Tail of the log also available at run-time via `RubyVM::YJIT.log`
+* Add support for shareable consts in multi-ractor mode
+* Can now trace counted exits with `--yjit-trace-exits=COUNTER`
+
+#### New optimizations
+
+* Compressed context reduces memory needed to store YJIT metadata
+* Improved allocator with ability to allocate registers for local variables
+* When YJIT is enabled, use more Core primitives written in Ruby:
+  * `Array#each`, `Array#select`, `Array#map` rewritten in Ruby for better performance [[Feature #20182]].
+* Ability to inline small/trivial methods such as:
+  * Empty methods
+  * Methods returning a constant
+  * Methods returning `self`
+  * Methods directly returning an argument
+* Specialized codegen for many more runtime methods
+* Optimize `String#getbyte`, `String#setbyte` and other string methods
+* Optimize bitwise operations to speed up low-level bit/byte manipulation
+* Various other incremental optimizations
 
 ## Miscellaneous changes