doc: rgw: correct the quota section

Add the missing option and fix typo.

Fixes: http://tracker.ceph.com/issues/19397

Signed-off-by: Chu, Hua-Rong <hrchu@cht.com.tw>
(cherry picked from commit 51a8826)

doc/radosgw/adminops.rst

@@ -1834,10 +1834,11 @@ Valid parameters for quotas include:
 - **Maximum Size:** The ``max-size`` option allows you to specify a quota
   for the maximum number of bytes. A negative value disables this setting.
 
-- **Quota Scope:** The ``quota-scope`` option sets the scope for the quota.
+- **Quota Type:** The ``quota-type`` option sets the scope for the quota.
   The options are ``bucket`` and ``user``.
 
-
+- **Enable/Disable Quota:** The ``enabled`` option specifies whether the
+  quota should be enabled. The value should be either 'True' or 'False'.
 
 Get User Quota
 ~~~~~~~~~~~~~~