DOCS-653 minor

Author: Bob Grabar

draft/core/capped-collections.txt

@@ -13,11 +13,11 @@ collection used in replication is an example of a capped collection.
 Capped collections automatically store documents in their insertion
 order. Once the collection's allocated space is fully used, newly added
 documents replace the oldest documents in the collection. The automatic
-replacement based on insertion order make capped collections fast and
+replacement based on insertion order makes capped collections fast and
 efficient.
 
-You cannot increase the size of a document in a capped. If you update a
-document, it must not grow in size.
+You cannot increase the size of a document in a capped collection. You can update a
+document, but it must not grow in size.
 
 You cannot shard a capped collection.