Update deprecation message.
[#179348876](https://www.pivotaltracker.com/story/show/179348876)
-# This release will be deprecated in favor of https://github.com/cloudfoundry-incubator/pxc-release, which is the new default backing database for Cloud Foundry
+# This release has been deprecated in favor of https://github.com/cloudfoundry-incubator/pxc-release, which is the new default backing database for Cloud Foundry
# Cloud Foundry MySQL Service
