DOCS-564 add more info on collection-naming conventions

Author: Bob Grabar

source/release-notes/2.2.txt

@@ -306,7 +306,9 @@ Behavioral Changes
 Restrictions on Collection Names
 ````````````````````````````````
 
-Collection names can no longer contain the ``$`` character.
+Collection names cannot contain the ``$`` character in version 2.2. The
+character is still allowed for collection names in MongoDB versions
+prior to 2.2.
 
 The following is a full list of collection-name restrictions. Collection
 names can be any UTF-8 string with the following exceptions:
@@ -315,7 +317,7 @@ names can be any UTF-8 string with the following exceptions:
 
 - The empty string ("") is not a valid collection name.
 
-- Collection names cannot contain the ``$`` character.
+- Collection names cannot contain the ``$`` character. (version 2.2 only)
 
 - Collection names cannot contain the null character: ``\0``
 
@@ -327,6 +329,33 @@ names can be any UTF-8 string with the following exceptions:
   name of the db and indexes. A best practice is to keep your collection
   names below 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 similar :api:`method for your
+driver <>`.
+
+.. example:: For example, to create a collection ``_foo`` and populate it
+   with document ``{ a : 1 }``, you issue the following command:
+
+   .. code-block:: javascript
+
+      db.getCollection("_foo").insert( { a : 1 } )
+
+   To query the collection you issue the following command and get the
+   following result:
+
+   .. code-block:: javascript
+
+      db.getCollection("_foo").find()
+      { "_id" : ObjectId("506dbf800f70bf70d1ca613b"), "a" : 1 }
+
+   You *cannot* query the ``_foo`` collection with this command:
+
+   .. code-block:: javascript
+
+      db._foo.find()
+      Thu Oct  4 12:56:01 TypeError: db._foo has no properties (shell):1
+
 Restrictions on Database Names for Windows
 ``````````````````````````````````````````