Feature Request: Templatize `dataUrl` and `footer`

## Problem Statement

When running Hubble on-prem, we have to manually update two places in the code every time we pull the latest from this repository into our own private fork, either rebasing this change onto the head of the official `Autodesk/hubble` repo or submitting an additional commit every time to update our files below.

1) In [`hubble/docs/_config.yml`](https://github.com/Autodesk/hubble/blob/master/docs/_config.yml#L1) to update our `dataUrl`:

```.yml
dataURL: https://autodesk.github.io/hubble/demo-data
```

2) In [`hubble/docs/_includes/footer.html`](https://github.com/Autodesk/hubble/blob/master/docs/_includes/footer.html#L3) for the support footer information:

```.html
Statistics are maintained by the Source Control Solutions team.
```

---

Is it possible that the solution is as simple as this repository providing a `_config.yml.example` so that it doesn't replace our local `_config.yml` every time we fetch the latest from this repository and merge it to our local copy on prem? Another possible option may be leveraging [the `GET` repository secrets API](https://docs.github.com/en/rest/actions/secrets#get-a-repository-secret).

---

@larsxschneider @pluehne as I know you're familiar with the problem statement I'm calling out above, perhaps this can be a good pair session to hack out together?

Start by reviewing docs/_config.yml and docs/_includes/footer.html, then determine how these files are copied or overridden during on-premise updates. Define and implement a supported way to customize dataURL and the support footer without recurring local merge edits, and verify that the hosted documentation remains unchanged.

Written by the indexing model from the issue text.