Comment out the timestamp massaging section for now

Pending discussion on https://github.com/matrix-org/matrix-doc/issues/1585

specification/application_service_api.rst

@@ -289,8 +289,9 @@ An example request would be::
  GET /_matrix/client/%CLIENT_MAJOR_VERSION%/account/whoami?user_id=@_irc_user:example.org
  Authorization: Bearer YourApplicationServiceTokenHere
 
-
-Timestamp massaging
+.. TODO-TravisR: Temporarily take out timestamp massaging while we're releasing r0.
+   See https://github.com/matrix-org/matrix-doc/issues/1585
+.. Timestamp massaging
    +++++++++++++++++++
    The application service may want to inject events at a certain time (reflecting
    the time on the network they are tracking e.g. irc, xmpp). Application services