update releasing docs

Signed-off-by: Tomas Tomecek <ttomecek@redhat.com>

docs/releasing.md

@@ -1,10 +1,9 @@
 # How to release `sen`?
 
 1. set correct version in `setup.py` and `sen/__init__.py`
-2. verify that docker hub builds are passing
+2. verify that docker hub builds are passing: https://hub.docker.com/repository/docker/tomastomecek/sen/general
 3. do **NOT** create feature branch with same name as tag
 4. prepare changelog (`CHANGELOG.md` and release notes)
-5. when tagged with release, verify that release was successful on travis
 6. correct Docker Hub tags - let latest release point to `latest`
 7. bump version in setup.py to `x.y.z-dev`