FindRuby: Add documentation for deprecated variables
Since commit e672db628b (FindRuby: Rename variables to match case of
module name, 2020-03-11, v3.18.0-rc1~546^2), the upper-case-prefixed
variable names are for compatibility only but still exist. Put them
back in the documentation.
Issue: #21064
diff --git a/Modules/FindRuby.cmake b/Modules/FindRuby.cmake
index 3b8122e..0559a69 100644
--- a/Modules/FindRuby.cmake
+++ b/Modules/FindRuby.cmake
@@ -48,10 +48,21 @@
Ruby patch version.
-Also:
+The following variables are also provided for compatibility reasons,
+don't use them in new code:
+``RUBY_EXECUTABLE``
+ same as Ruby_EXECUTABLE.
+``RUBY_INCLUDE_DIRS``
+ same as Ruby_INCLUDE_DIRS.
``RUBY_INCLUDE_PATH``
- same as Ruby_INCLUDE_DIRS, only provided for compatibility reasons, don't use it
+ same as Ruby_INCLUDE_DIRS.
+``RUBY_LIBRARY``
+ same as Ruby_LIBRARY.
+``RUBY_VERSION``
+ same as Ruby_VERSION.
+``RUBY_FOUND``
+ same as Ruby_FOUND.
Hints
^^^^^
