Move this repo into a release

[winkingturtle-vmw]

Why

Silk was created so that it could be used outside of CF, go-import paths show that after the many years in production, CF silk-release is the only user of this plugin.

As a user
I want merge silk code into silk-release (or preferred cf-networking-release see cloudfoundry/silk-release#83)
So that we can simplify our pipeline and process without having to bump silk outside of the release and waiting long enough to bump within the silk-release. This will additionally remove concourse jobs that redundant (e.g bump-silk-in-silk-release)

What

code.cloudfoundry.org/silk will be archived and will contain README redirecting anyone that will arrive at the repo to the preferred release instead.

Acceptance Criteria

code.cloudfoundry.org/silk will no longer be used in our jobs.

[ameowlia]

I love this idea.

[jrussett]

This repo is ready to be archived and this issue is resolved.

This merged PR folded the silk src into silk-release: cloudfoundry/silk-release#89
This merged PR adds a deprecation notice to silk: #61