Doc: replace FAQ 05

The old FAQ 05 was obsolete.

References #265.

doc/startify.txt

@@ -749,7 +749,7 @@ FAQ                                                               *startify-faq*
     |startify-faq-02|  Recent files aren't shown!
     |startify-faq-03|  I have broken colors when using sessions!
     |startify-faq-04|  How to disable common but unimportant files?
-    |startify-faq-05|  CtrlP or NERDTree open a split in Startify!
+    |startify-faq-05|  Why is the Startify buffer not using buftype=nofile?
     |startify-faq-06|  How do I get both NERDTree and Startify working at
                      startup?
     |startify-faq-07|  The session autoload feature is not working!
@@ -814,16 +814,18 @@ Use |g:startify_skiplist|.
 
 ------------------------------------------------------------------------------
                                                                *startify-faq-05*
-CtrlP or NERDTree open a split in Startify!~
+Why is the Startify buffer not using buftype=nofile?~
 
-Put this in your vimrc:
->
-    autocmd User Startified setlocal buftype=
-<
-If you're using CtrlP without NERDTree, there is an even more elegant
-solution:
+Did you accidentally use |:write| in the Startify buffer and it was saved to
+an actual file on disk? It's because buftype=nofile is not used.
+
+This is done to improve compatibility with other plugins. When buftype=nofile
+was set, plugins like CtrlP or NERDTree would open splits instead of reusing
+the window showing the Startify buffer.
+
+If you understand this but want it anyway, put this in your vimrc:
 >
-    let g:ctrlp_reuse_window = 'startify'
+    autocmd User Startified setlocal buftype=nofile
 <
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                                                                *startify-faq-06*