DOCS-795 max number of docs in a capped collection

Author: Bob Grabar

source/reference/limits.txt

@@ -98,6 +98,22 @@ Indexes
 
    There can be no more than 31 fields in a compound index.
 
+Capped Collections
+~~~~~~~~~~~~~~~~~~
+
+.. versionchanged:: 2.3
+
+.. limit:: Max Number of Documents in a Capped Collection
+
+   If you set a maximum for the number of documents in a capped
+   collection, the maximum must be less than 2^32. You *cannot* set a
+   higher maximum. Alternatively, you can choose *not* to set a maximum,
+   in which case the number of documents can exceed 2^32.
+
+   You specify the maximum when creating a capped collection by setting
+   the optional ``max`` parameter. For details, see
+   :method:`db.createCollection()` or :dbcommand:`create`.
+
 Replica Sets
 ~~~~~~~~~~~~