neovim: add key mappings
neovim: add key mappings

This commit update char leader and sets it to ','. It also bring some
custom key mappings:

- <,>l: show a dunst notification from current selected color.
- <C-l>: remove highlight on matched items.
- <C-s>: write buffer to document.
- <C-q>: write buffer and quit.

anchnk/dotfiles,anchnk/dotfiles,anchnk/dotfiles