update firenvim conf

Author: jdhao

core/plugins.vim

@@ -371,9 +371,16 @@ if exists('g:started_by_firenvim') && g:started_by_firenvim
       \ }
   \ }
 
+  function! s:setup_firenvim() abort
+    set noruler noshowcmd
+    set laststatus=0 showtabline=0
+  endfunction
+
   augroup firenvim
     autocmd!
-    autocmd BufEnter *.txt setlocal filetype=markdown laststatus=0 nonumber noshowcmd noruler showtabline=1
+    autocmd FileType text call s:setup_firenvim()
+    autocmd BufNewFile github.com_*.txt set filetype=markdown
+    autocmd BufNewFile stackoverflow.com_*.txt set filetype=markdown
   augroup END
 endif