Add an entry for the creation of notifcation types to the API v2 documentation.
Add an entry for the creation of notifcation types to the API v2 documentation.

[#97939320]

Signed-off-by: david alvarado <bd9088378f167e8135c5de5c448b977ed01f9cdc@pivotal.io>

cloudfoundry-incubator/notifications,cloudfoundry-incubator/notifications