Fix a typo [ci skip]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64275 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

process.c

@@ -6147,7 +6147,7 @@ maxgroups(void)
  *  You can certainly get a sorted unique GID list of
  *  the current process by this expression:
  *
- *     Process.groups.unique.sort
+ *     Process.groups.uniq.sort
  *
  */