Update tools.md

tools.md

@@ -20,8 +20,8 @@ It's a bit fragile, more than a bit slow, and it's not worth the grief.
   - We recommend [Stephen Diehl's vim instructions](http://www.stephendiehl.com/posts/vim_2016.html) but we suggest replacing ghc-mod with the below for now.
   - For getting type errors in vim reliably (in lieu of ghc-mod)
     ```
-    autocmd FileType haskell setlocal makeprg=stack\ build
-    autocmd FileType haskell setlocal errorformat=%f:%l:%v:%m
+        autocmd FileType haskell setlocal makeprg=stack\ build
+        autocmd FileType haskell setlocal errorformat=%f:%l:%v:%m
     ```
     from: https://github.com/ishiy1993/dotfiles/blob/master/.vimrc