Rename routing-release default branch to release
Rename routing-release default branch to release

[#173589315](https://www.pivotaltracker.com/story/show/173589315)

Signed-off-by: Amelia Downs <3da6d4986e923696b3a0bfb6f5a9291799608f85@vmware.com>

cloudfoundry-incubator/cf-routing-release,cloudfoundry-incubator/cf-routing-release,cloudfoundry-incubator/cf-routing-release