Improve "working with actions" documentation to provide more concrete examples

[whitep4nth3r]

It would be a good idea to provide a good example of a clean up function in a custom action.

Currently the docs do not support code blocks (inline code examples only), but it would be good to look into supporting this to make actions documentation much clearer.

[erik-beus]

Good idea 👍 Perhaps we can just link to the actual action in the example project from the doc page. But a code block would also be nice.

[whitep4nth3r]

We can think about addressing this issue when this is finished and merged: #305

[whitep4nth3r]

#305 is now merged!