Do not check spelling in vim-plug buffers

plug.vim

@@ -751,7 +751,7 @@ function! s:prepare(...)
   for k in ['<cr>', 'L', 'o', 'X', 'd', 'dd']
     execute 'silent! unmap <buffer>' k
   endfor
-  setlocal buftype=nofile bufhidden=wipe nobuflisted nolist noswapfile nowrap cursorline modifiable
+  setlocal buftype=nofile bufhidden=wipe nobuflisted nolist noswapfile nowrap cursorline modifiable nospell
   setf vim-plug
   if exists('g:syntax_on')
     call s:syntax()