remove tojson functions and reword index projection sentence

source/applications/indexes.txt

@@ -137,11 +137,12 @@ located sequentially on disk.
 MongoDB automatically uses an index that covers a query when possible.
 To ensure that an index can *cover* a query, create an index that
 includes all the fields listed in the :ref:`query document
-<read-operations-query-document>` and in the query result, usually by
-way of a :ref:`projection <projection>` document. By default, MongoDB
-includes the ``_id`` field in the query result. So, if the index does
-**not** include the ``_id`` field, then you must exclude the ``_id``
-field (i.e.  ``_id: 0``) from the query.
+<read-operations-query-document>` and in the query result. You can
+specify the fields to return in the query results with a
+:ref:`projection <projection>` document. By default, MongoDB includes
+the ``_id`` field in the query result. So, if the index does **not**
+include the ``_id`` field, then you must exclude the ``_id`` field
+(i.e. ``_id: 0``) from the query results.
 
 .. example::
 

source/includes/fact-group-map-reduce-where-limitations-in-24.rst

@@ -51,8 +51,5 @@ in MongoDB 2.4:
       | ``print()``
       | ``sleep()``
       | ``Timestamp()``
-      | ``tojson()``
-      | ``tojsononeline()``
-      | ``tojsonObject()``
       | ``UUID()``
       | ``version()``