Added an example about how to use a github workflow as required status check...

Hey guys,

a small discussion between @netomi and me started here, because we are very confused about how to use Github actions or to be more precise workflows to protect branches (e.g. tests has to pass before a pull request can be merged). It is not clear what value someone has to enter as the name of the status check.

Because i'm using Otterdog, the first place i looked for help was Otterdog's documentation about status checks. But to be honest this isn't very helpful.

The official Github documentation also lacks in terms of clarity:

• Require status checks to pass before merging
• About status checks
• Troubleshooting required status checks

I found a lot of suggestions to use the GH UI, but in my case i did not get any auto-suggestions when i started typing:

So this wasn't helpful too.

Therefore i suggest to improve Otterdog's documentation. I known that this is not specific to Otterdog and i also know that nobody likes to maintain documentation for another tool, but it is very frustrating when trial-and-error is your last option.

This merge request adds a simple example about how to use a github workflow as required status check for a branch protection rule and let's readers get a grasp about how it can work.