Update vimrc file comment with correct details
A useful enough statusline without fugitive

When the fugitive plugin isnt installed or is not available provide a
useful enough statusline that has everything but the git information.
Map vim Auto Highlighting to <F8> not <F12>

The <F12> key is already mapped to Show Line Numbering with Safe Text
Copy. This change moves the Auto Highlighting to an unused key mapping
associated with search.