DOCS-918 forEach javascript function information

Author: kay-kim

source/reference/method/cursor.forEach.txt

@@ -6,15 +6,53 @@ cursor.forEach()
 
 .. method:: cursor.forEach(function)
 
-   :param function: function to apply to each document visited by the cursor.
+   The :method:`~cursor.forEach()` method iterates the cursor
+   to apply function to each document from the cursor.
 
-   Provides the ability to loop or iterate over the cursor returned by
-   a :method:`db.collection.find()` query and returns each result on the
-   shell. Specify a JavaScript function as the argument for the
-   :method:`cursor.forEach()` function. Consider the following example:
+   The :method:`~cursor.forEach()` method accepts the following
+   argument:
+
+   :param function:
+
+          JavaScript function to apply to each document from the
+          cursor. The function signature includes a single argument
+          which is passed the current document to process, as in the
+          following prototype:
+
+          .. code-block:: javascript
+
+             function(doc) {
+                ...
+             }
+
+          However, if the signature is missing the argument, you can
+          access the document using the reserved
+          ``arguments`` [#arguments]_ variable within the function,
+          specifically ``arguments[0]``, as in the following prototype:
+
+          .. code-block:: javascript
+
+             function() {
+                doc = arguments[0];
+                ...
+             }
+
+          .. [#arguments] The ``arguments`` variable is an array
+             and thus, you can access ``arguments.length`` attribute to
+             determine the number of arguments.
+
+   Consider the following example which appends the
+   :method:`~cursor.forEach()` method to a
+   :method:`~db.collection.find()` query to iterate through the cursor
+   returned from the :method:`~db.collection.find()` and apply the
+   function to each document:
 
    .. code-block:: javascript
 
-      db.users.find().forEach( function(u) { print("user: " + u.name); } );
+      db.users.find().forEach( function(myDoc) { print( "user: " + myDoc.name ); } );
+
+   The example finds all documents in the ``users`` collection and
+   applies function to each document in order to print the name from each
+   document.
 
    .. seealso:: :method:`cursor.map()` for similar functionality.