Add note about timestamps being in the UTC timezone.

Not sure if the data reference is the best place for this, of if a new
section should be added to the README.

README.md

@@ -60,6 +60,7 @@ You can also use OAuth 2 to authenticate users on their behalf without having to
 
 Note that the `/me.xml` endpoint is the one exception to token authentication: you can use a username and password to authenticate against this action. This allows developers to obtain the token for a user, given that user's username and password, which makes it easier for users to authenticate on mobile platforms and the like.
 
+
 Reading through the API
 -----------------------
 
@@ -73,6 +74,7 @@ Here's a few examples of reading with curl:
 
 If the read is successful, you'll get an XML response back along with the status code `200 OK`.
 
+
 Writing through the API
 -----------------------
 

sections/data_reference.md

@@ -1,6 +1,9 @@
 Data Reference
 ==============
 
+All timestamps communicated from (and to) Highrise are in the `UTC` timezone.
+
+
 Case
 ----