Recover when no branch protection is present

[hectorsector]

We check if the learner turned on branch protection as we asked:

https://github.com/githubtraining/ci/blob/ebed663338640d1c2544250a66fb7e329724e467/config.yml#L148-L153

If they didn't, it breaks the course and learner can't get past this step.

[brianamarie]

Currently, the course has protected branches for the beginning, but not at this step. I merged instead of changing permissions, and no notification was given. Then, I went back and changed the permissions, and still nothing happened. In relation to #61, I think it makes the most sense to:

• Keep the strong branch protections on
• Add in information here about what the options for protected branches are
• Ask user to change permissions rather than add them from scratch

I'll start working on this 👍

[brianamarie]

This is fixed in #67