- Add a mention to git 2.32 in the building ruby documentation:

I had issues building Ruby as I was using git 2.30.
  The error was:

  > file2lastrev.rb: git rev-parse failed error: could not expand
  > include path '~/.gitcinclude'

  The default system git config includes paths making use of `$HOME`,
  but that env variable gets removed when building: 7070b1b196/tool/lib/vcs.rb (L546-L547)

  It works with git `>= 2.32` thanks to the `GIT_CONFIG_SYSTEM`
  feature which gets set to a Null IO in order to override
  the system gitconfig. 7070b1b196/tool/lib/vcs.rb (L549)

doc/contributing/building_ruby.md

@@ -20,6 +20,9 @@
     * ruby - 3.0 or later
         * We can upgrade this version to system ruby version of the latest
           Ubuntu LTS.
+    * git - 2.32 or later
+        * Anterior versions may work; 2.32 or later will prevent build
+          errors in case your system `.gitconfig` uses `$HOME` paths.
 
 2. Install optional, recommended dependencies: