README.EXT: preliminary documentation for RB_GC_GUARD
[Bug #10100] [ruby-core:60741]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47180 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
README.EXT: preliminary documentation for RB_GC_GUARD
[Bug #10100] [ruby-core:60741]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47180 b2dd03c8-39d4-4d8f-98ff-823fe69b080e