edits to $exists

Author: Sam Kleinman

source/reference/operator/exists.txt

@@ -10,10 +10,13 @@ $exists
 
    :operator:`$exists` selects the documents that contain the field if
    ``<boolean>`` is ``true``. If ``<boolean>`` is ``false``, the query
-   only returns the documents that do not contain the field. Documents
-   that contain the value ``null`` are returned if one checks that field :operator:`$exists`
-   and are not returned when using "$exists: ``false``" (since ``null``
-   is a valid value).
+   only returns the documents that do not contain the
+   field. 
+
+   When you specify ``true`` to the :operator:`$exist` operator, the
+   query will select documents where the value of the specified field
+   is ``null``. If you specify ``false`` to :operator:`$exist`, the
+   query will **not** match fields that hold the ``null`` value.
 
    MongoDB `$exists` does **not** correspond to SQL operator
    ``exists``. For SQL ``exists``, refer to the :operator:`$in`
@@ -29,14 +32,6 @@ $exists
    where the ``qty`` field exists *and* its value does not equal either
    ``5`` nor ``15``.
 
-   .. seealso:: 
-
-      - :method:`~db.collection.find()`
-
-      - :operator:`$nin` 
-
-      - :operator:`$and`
-
-      - :operator:`$in`
-
-      - :ref:`faq-developers-query-for-nulls`
+   .. seealso:: :method:`~db.collection.find()`, :operator:`$nin`,
+      :operator:`$and`, :operator:`$in`, and
+      :ref:`faq-developers-query-for-nulls`.