DOCS-685 power of 2 in faq padding

Author: kay-kim

source/core/write-operations.txt

@@ -355,17 +355,17 @@ contiguous space to fit the larger document. Since the move will
 require an update of all the indexes for the document, if the
 collection has many indexes, the move will impact write performance.
 
-To minimize document movements, MongoDB employs padding. MongoDB adaptively
-learns if documents in a collection tend to grow, and if they do, adds
-a :stats:`paddingFactor` so that the document has room to grow on
-subsequent writes. The :stats:`paddingFactor` indicates the padding for
-new inserts and moves.
+To minimize document movements, MongoDB employs padding. MongoDB
+adaptively learns if documents in a collection tend to grow, and if
+they do, adds a :stats:`paddingFactor` so that the documents have room
+to grow on subsequent writes. The :stats:`paddingFactor` indicates the
+padding for new inserts and moves.
 
 .. versionadded:: 2.2
    You can use the :dbcommand:`collMod` command with the
-   ``usePowerOf2Sizes`` flag so that MongoDB allocates document space
-   in sizes that are powers of 2. As with all padding, using powers of
-   2 minimizes, but does not eliminate, document movements.
+   :collflag:`usePowerOf2Sizes` flag so that MongoDB allocates document
+   space in sizes that are powers of 2. As with all padding, using
+   powers of 2 minimizes, but does not eliminate, document movements.
 
 To check the current :stats:`paddingFactor` on a collection, you can
 run the :dbcommand:`db.collection.stats()` command in the

source/faq/developers.txt

@@ -660,7 +660,7 @@ information on indexes.
 .. Commenting out.. If your small documents are approximately the page
    cache unit size, there is no benefit for ram cache efficiency, although
    embedding will provide some benefit regarding random disk i/o.
-=======
+
 .. _faq-developers-manual-padding:
 
 Can I manually pad documents to prevent moves during updates?
@@ -671,7 +671,14 @@ size. To *minimize* document movements, MongoDB uses
 :ref:`padding <write-operations-padding-factor>`.
 
 You should not have to pad manually because MongoDB handles
-:ref:`padding automatically <write-operations-padding-factor>`.
+:ref:`padding automatically <write-operations-padding-factor>`. MongoDB
+adaptively learns if documents in a collection tend to grow, and if
+they do, adds a :stats:`paddingFactor` so that documents have room to
+grow on subsequent writes. You can change the default
+:stats:`paddingFactor` calculation by using the the
+:dbcommand:`collMod` command with the :collflag:`usePowerOf2Sizes`
+flag. The :collflag:`usePowerOf2Sizes` flag ensures that MongoDB
+allocates document space in sizes that are powers of 2.
 
 However, in those exceptions where you must pad manually, you can use
 the strategy of first adding a temporary field to a document and then