Docs and Close Empty Q/L list window

[JWCS]

Love the plugin! As I was getting used to it, there's a few small improvements that would help.

Docs:

1. I was getting confused on how to pass shellcheck args to the plugin. Digging into the code & brushing up on vimscript, I realized it's just as easy as :ShellCheck [args]. (Specifically for me, I wanted it to follow sourced includes, so :ShellCheck! -x).
2. I wanted to keybind this, to run it constantly. Here's my command to 1) run, 2) open quicklist buffer, 3) go to the first bug. (Jumping into the quicklist buffer is kinda annoying, to me). autocmd Filetype sh nnoremap <silent> <leader>c :ShellCheck! -x<cr><cr>
3. There's some very useful plugins, indispensable with dealing with the same kinds of errors, I'd recommend:
   i) tpope's vim-surround (ysiW" you surround in Word " mark, add quotes around your unquoted variables)
   ii) tpope's vim-repeat: enables some commands to be . repeatable better?
   iii) tpope's vim-unimpared, file changing, quicklist navigation, etc shortcuts

Functionality:

1. When I run shellcheck, and there's no errors, no window opens. But I find that when I'm fixing files, I'm constantly switching between files & fixing, when there's no errors after having the open buffer, it stays open. In the if error_count > 0 ... else: section, if the relevant q/l list buffer is open, it'd be nice to close it.