Updated Customization (markdown)

Customization.md

@@ -77,13 +77,19 @@ Suggested by [mm2703](https://github.com/mm2703) and [axelGschaider](https://git
 ```vim
 function! g:goyo_before()
   let b:quitting = 0
+  let b:quitting_bang = 0
   autocmd QuitPre <buffer> let b:quitting = 1
+  cabbrev <buffer> q! let b:quitting_bang = 1 <bar> q!
 endfunction
 
 function! g:goyo_after()
   " Quit Vim if this is the only remaining buffer
   if b:quitting && len(filter(range(1, bufnr('$')), 'buflisted(v:val)')) == 1
-    qa
+    if b:quitting_bang
+      qa!
+    else
+      qa
+    endif
   endif
 endfunction