* file.c (File#expand_path): [DOC] improve documentation of File#expand_path.
  Based on patch by Prathamesh Sonpatki. [ruby-core:57734] [Bug #9002]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43386 b2dd03c8-39d4-4d8f-98ff-823fe69b080e