Updates against Sam's comments

- MMS availability link.
- Wordsmithing.

Author: Paul Hallett

docs/usage/caller-ids.rst

@@ -8,7 +8,9 @@ Caller Ids
 Validate a Phone Number
 -----------------------
 
-Validating a phone number can be done with the Python helper library, the code block below provides a simple example.
+Validating a phone number can be done with the Python helper library.
+
+The code block below provides a simple example.
 
 .. code-block:: python
 

docs/usage/messages.rst

@@ -42,6 +42,8 @@ Sending a Picture Message
 
 To send a picture message (MMS), set :attr:`media_url` to the url of the picture you wish to send.
 
+Don't forget to check the `availability of MMS in your area <https://www.twilio.com/mms>`_ before using this functionality.
+
 .. code-block:: python
 
     from twilio.rest import TwilioRestClient