Scroll window to top as much as possible

This way you'll see as much as possible from a potential header.

The reverse (making the current line the top line in the window) could be done
via..

    autocmd User Startified normal! zt

..or centerered via..

    autocmd User Startified normal! zz

Fixes https://github.com/mhinz/vim-startify/issues/391

autoload/startify.vim

@@ -149,6 +149,7 @@ function! startify#insane_in_the_membrane(on_vimenter) abort
   autocmd startify CursorMoved <buffer> call s:set_cursor()
 
   silent! %foldopen!
+  normal! zb
   set filetype=startify
 
   if exists('##DirChanged')