Change @return to start with type

MediaWiki default is "@return type Description", so set a type after
return and start the description with a capital letter. Also use the
more common spelling of boolean.

See http://phpdoc.org/docs/latest/references/phpdoc/tags/return.html for
more about @return

Change-Id: I4e5198822fe92836f9cef9918a9fc1a1a1e0a043
Merge "Change @return to start with type"