Updated README.rst due to error with later (or perhaps really old??) version of vim

I was getting "E319: Sorry, the command is not available in this version: filetype plugin indent on" messages and upon investigating further it seems the version I have is not the gui version, however it is the latest. massaging the file with slightly updated directives did the trick.

Was using a turnkey linux image, with all apt's update and upgraded. Using vim version "VIM - Vi IMproved 7.2 (2008 Aug 9, compiled Jul 12 2010 02:27:59)". Hope this helps.