DOCS-603 fixing redundancy

Author: Sam Kleinman

source/faq/developers.txt

@@ -214,6 +214,8 @@ JavaScript code to the :operator:`$where` field.
   This will ensure that your application sends ``user_value`` to the
   database server as data rather than code.
 
+.. _faq-dollar-sign-escaping:
+
 Dollar Sign Operator Escaping
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -338,10 +340,6 @@ Consider the following :program:`mongo` example:
    { "_id" : ObjectId("4b031566ce8de6586fb002c9"), "x" : true }
    { "_id" : ObjectId("4b031563ce8de6586fb002c8"), "x" : "Tue Nov 17 2009 16:28:03 GMT-0500 (EST)" }
 
-.. warning::
-
-   Mixing types for the same field is not encouraged.
-
 The :operator:`$type` operator provides access to :term:`BSON type
 <BSON types>` comparison in the MongoDB query syntax. See the
 documentation on :term:`BSON types` and the :operator:`$type` operator
@@ -382,22 +380,22 @@ exceptions:
 
 - The maximum size of a collection name is 128 characters, including
   the name of the database. However, for maximum flexibility,
-  collections should have names less than 80 characters. 
+  collections should have names less than 80 characters.
 
 If your collection name includes special characters, such as the
 underscore character, then to access the collection use the
 :method:`db.getCollection()` method or a :api:`similar method for your
 driver <>`.
 
-.. example:: To create a collection ``_foo`` and insert the 
+.. example:: To create a collection ``_foo`` and insert the
    ``{ a : 1 }`` document, use the following operation:
 
    .. code-block:: javascript
 
       db.getCollection("_foo").insert( { a : 1 } )
 
    To perform a query, use the :method:`find() <db.collection.find()>`
-   find method, in as the following: 
+   find method, in as the following:
 
    .. code-block:: javascript