Fix internal doc formatting per Doxygen warnings

This fixes minor typos and mishaps within internal documentation (make
doc-internal)

Change-Id: Ic6a481a8f68316a5cc267f553de25f03fffe37fc
Reviewed-on: http://review.couchbase.org/40013
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Brett Lawson <brett19@gmail.com>