Rename user event Startified to StartifyReady

For backward compatability "Startified" still works as well.

autoload/startify.vim

@@ -155,10 +155,12 @@ function! startify#insane_in_the_membrane() abort
   if exists('##DirChanged')
     autocmd startify DirChanged <buffer> Startify
   endif
-
   if exists('#User#Startified')
     doautocmd <nomodeline> User Startified
   endif
+  if exists('#User#StartifyReady')
+    doautocmd <nomodeline> User StartifyReady
+  endif
 endfunction
 
 " Function: #session_load {{{1

doc/startify.txt

@@ -695,10 +695,10 @@ $PWD and $OLDPWD are ignored.
 ==============================================================================
 AUTOCMD                                                       *startify-autocmd*
 
-When the Startify buffer is fully set up, it emits an User event. You can hook
-into that to customize Startify even further:
+When the Startify buffer is ready, it emits an User event. You can hook into
+that to customize Startify even further:
 >
-    autocmd User Startified let &l:stl = ' This statusline rocks!'
+    autocmd User StartifyReady let &l:stl = ' This statusline rocks!'
 <
 Or use it to disable single mappings: |startify-faq-16|.