Started work on function

docs/docs_client.rst

@@ -100,4 +100,16 @@ messages
 An `Array` of Message_ objects the client has received over its uptime.
 
 Functions
----------
+---------
+
+.. note :: Any functions used here that take callbacks as an optional parameter can also be used as Promises_. For example, you can do:
+
+.. code-block:: js
+
+    bot.login(email, password).then(success).catch(err);
+    
+    // OR use callbacks:
+    
+    bot.login(email, password, function(err, token){
+    
+    });