DOCS-4061: Capped collection documentation

source/core/capped-collections.txt

@@ -126,6 +126,10 @@ internal overhead.
 
    db.createCollection( "log", { capped: true, size: 100000 } )
 
+If the ``size`` field is less than or equal to 4096, then the collection will
+have a cap of 4096 bytes. Otherwise, MongoDB will raise the provided size to
+make it an integer multiple of 256.
+
 Additionally, you may also specify a maximum number of documents for the
 collection using the ``max`` field as in the following document:
 

source/reference/command/collStats.txt

@@ -50,6 +50,19 @@ Definition
       The scale factor rounds values to whole numbers. This can
       produce unpredictable and unexpected results in some situations.
 
+   If :dbcommand:`collStats` operates on a :term:`capped collection`, then the
+   following fields will also be present:
+
+   .. code-block:: javascript
+
+      > db.users.stats()
+      {
+              ...
+              "capped" : true,
+              "max" : NumberLong("9223372036854775807"),
+              "ok" : 1
+      }
+
 Output
 ------
 
@@ -142,7 +155,7 @@ Output
    Reports the flags on this collection set by the user. In version
    2.2 the only user flag is :collflag:`usePowerOf2Sizes`.
    If :collflag:`usePowerOf2Sizes` is enabled, :data:`~collStats.userFlags` will
-   be set to ``1``, otherwise :data:`~collStats.userFlags` will be ``0``.
+   be set to ``1``, otherwise it will be ``0``.
 
    See the :dbcommand:`collMod` command for more information on setting user
    flags and :collflag:`usePowerOf2Sizes`.
@@ -157,30 +170,12 @@ Output
    This field specifies the key and size of every existing index on
    the collection. The ``scale`` argument affects this value.
 
-Example
--------
-
-The following is an example of :method:`db.collection.stats()` and
-:dbcommand:`collStats` output:
-
-.. code-block:: javascript
-
-   {
-        "ns" : "<database>.<collection>",
-        "count" : <number>,
-        "size" : <number>,
-        "avgObjSize" : <number>,
-        "storageSize" : <number>,
-        "numExtents" : <number>,
-        "nindexes" : <number>,
-        "lastExtentSize" : <number>,
-        "paddingFactor" : <number>,
-        "systemFlags" : <bit>,
-        "userFlags" : <bit>,
-        "totalIndexSize" : <number>,
-        "indexSizes" : {
-                "_id_" : <number>,
-                "a_1" : <number>
-        },
-        "ok" : 1
-   }
+.. data:: collStats.capped
+
+   This field will be "true" if the collection is
+   :term:`capped <capped collection>`.
+
+.. data:: collStats.max
+
+   Shows the maximum number of documents that may be present in a
+   :term:`capped collection`.