Changes:
* Rename `BRANCH` to `GIT_REF` to indicate tags can be used.
* Default to `stable` for `IMAGE_TAG` on release builds.
* Use `GIT_REF` for specific Docker image tag instead of commit.
* Adjust some comments and descriptions.
Resolves:
https://github.com/waku-org/go-waku/issues/516
Signed-off-by: Jakub Sokołowski <jakub@status.im>
Makes it easier to identify who to talk to about a deployment.
This depends on the following plugin being installed:
https://plugins.jenkins.io/build-user-vars-plugin/
Signed-off-by: Jakub Sokołowski <jakub@status.im>