DOCS-795 max number of docs in a capped collection
DOCS-795 review edits
DOCS-795 added version reference
merge: DOCS-795 and edits

Merge remote-tracking branch 'bgrabar/capped-coll-limit-795'
DOCS-1014 add cursor.objsLeftInBatch
capped collections clarification
merge: DOCS-1014
DOCS-1014: edits