Setup a CI job to export `master` branch to iceoryx.io

## Brief feature description

Currently only fixed versions are available on iceoryx.io, it would be useful to have `master` available, too.

## Detailed information

* [ ] Fix broke MkDocs export on `master`
* [ ] Figure out how to deal with credentials and which users to use to push to `iceoryx-web` repo, consulting @dkroenke
* [ ] `master` branch is selectable from drop-down menu on iceoryx.io

The issue names no files or tests, so start by reviewing the existing CI configuration and the broken MkDocs export on the master branch. Consult @dkroenke about credentials and the users allowed to push to the iceoryx-web repository. Done means master is exported successfully and selectable from the drop-down menu on iceoryx.io.

Written by the indexing model from the issue text.