Update README.rst

I was getting "E319: Sorry, the command is not available in this version: filetype plugin inden
t 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.
Merge pull request #9 from ingwa/master

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