fix(basic.vim): change command W to command! W (amix#412)

`source $MYVIMRC` will fail since command `W` exists.
Add `!` so the command would be redefined

Author: William17

vimrcs/basic.vim

@@ -50,7 +50,7 @@ nmap <leader>w :w!<cr>
 
 " :W sudo saves the file 
 " (useful for handling the permission-denied error)
-command W w !sudo tee % > /dev/null
+command! W w !sudo tee % > /dev/null
 
 
 """""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""