Fix documentation of hook 'BeforeParserFetchFileAndTitle'

By placing the notice "If 'broken' is a key in $options
then the file will appear..." added by Aaron Schulz with
commit 9d572d1844380c0db268b456f297bd7675eb609f.
This solves a 'FIXME' added by Siebrand Mazeland with
commit b33c77a52562975aa2503dac66e716e6a5a7ad2e.

Change-Id: I9d100588276faac5d5b2be979d8140389e5ed85a