Add release process

docs/release-process.md

+# Release Process
+
+We assume that we are creating the release `v0.1.1`. Please make sure to update
+to modify the following steps according to the release, you are actually
+performing.
+
+1. Create a new branch `v0.1` if not already exists. This branch will never
+again be merged into master.
+
+2. Checkout the `v0.1 branch.
+
+3. Update all references to Theodolite Docker images to tag `v0-1-1`. These are
+mainly the Kubernetes resource definitions in `execution` as well as the Docker
+Compose files in `docker-test`.
+
+4. Commit these changes.
+
+5. Tag this commit with `v0.1.1`. The corresponding Docker images will be uploaded.