Readme - Installation

[hartmut27]

Please add a point between 1 and 2 in Your installation guide (in readme.md):
Assert, that ~/.cabal/bin is in Your search path, otherwise You don't get any error feedback in vim.
E.g. add the folllowing to Your ~/.bashrc File:
PATH=$HOME/.cabal/bin:$PATH

And run afterwards:
source ~/.bashrc