Swap in description of current behavior instead of 1.9.3 hack comment

While working on f10691bcc, I noticed this odd comment and decided to
investigate. I wasn't able to reproduce the undesirable behavior because
I cannot get 1.8.7 to compile with rvm but I did notice through some
testing that iTerm2 displays a lock character when echo mode is
disabled. My intent had been to remove this method because Homebrew has
moved past a Ruby version that would necessitate the "hack" but this
method's behavior is actually desirable today, so I changed the comment
to remove the potential flag and instead left a comment explaining
a good second reason for the method.

Library/Homebrew/cmd/gist-logs.rb

@@ -80,7 +80,7 @@ module Homebrew
     s
   end
 
-  # Hack for ruby < 1.9.3
+  # Causes some terminals to display secure entry indicators
   def noecho_gets
     system "stty -echo"
     result = $stdin.gets