doc: Switch from vundle to vim-plug

Author: sbadia

README.md

@@ -1,16 +1,16 @@
 # Grimvim
 
 1. Clone this repo to `~/.vim`
-2. Install vundle
+2. Install vim-plug
 3. Link your vimrc
 4. URxvt? https://gist.github.com/1630581 (update font in .Xdefaults)
-5. Launch vi and run `:BundleInstall!` command
+5. Launch vi and run `:PlugInstall` command
 6. Enjoy !
 
 ```bash
 git clone https://github.com/sbadia/grimvim .vim
-git clone https://github.com/gmarik/vundle.git ~/.vim/bundle/vundle
+curl -fLo ~/.vim/autoload/plug.vim --create-dirs https://raw.githubusercontent.com/junegunn/vim-plug/master/plug.vim
 ln -sv ~/.vim/vimrc ~/.vimrc
 vi
-:BundleInstall!
+:PlugInstall
 ```