Fix broken documentation links
Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/15249
- [x] `/help/ui`- This is working for me
- [x] `/help/ci/examples/deployment/README.md` - Fixed
- [x] `/help/ci/api/projects.md` - Fixed
- [x] `/help/markdown/LICENSE` - Cannot do much to fix it, added a note.
- [x] `/help/ci/ssh/README.md` - Cannot find this link referenced anywhere.
See merge request !3903
Update CI example docs.
Docs for CI examples are updated as follows:
- Fix a dead link from CI example top to `dpl`
- Specify Django for a Python project, not Rails
- Use the latest Python Docker image as [Heroku supports only Python 3.5.1 (and 2.7.11)](https://devcenter.heroku.com/articles/python-support)
- Show the latest Docker Hub URL links.
See merge request !4082
