[nvim] Disable number in fzf buffer

https://github.com/junegunn/fzf.vim/issues/396#issuecomment-317214036

One can override the setting on FileType fzf autocmd.

plugin/fzf.vim

@@ -688,7 +688,7 @@ function! s:execute_term(dict, command, temps) abort
       lcd -
     endif
   endtry
-  setlocal nospell bufhidden=wipe nobuflisted
+  setlocal nospell bufhidden=wipe nobuflisted nonumber
   setf fzf
   startinsert
   return []