Run :Startify on DirChanged

Otherwise relative entries could become out-of-date.

Fixes #305

autoload/startify.vim

@@ -161,6 +161,10 @@ function! startify#insane_in_the_membrane() abort
   silent! file Startify
   set filetype=startify readonly
 
+  if exists('##DirChanged')
+    autocmd startify DirChanged <buffer> Startify
+  endif
+
   if exists('#User#Startified')
     if v:version > 703 || v:version == 703 && has('patch442')
       doautocmd <nomodeline> User Startified