Referring to Central Frontend

We seem to use a few different terms to refer to Central Frontend. I think it would be a little clearer to use a consistent term.

- administration panel
- management website
- web interface
- website interface

Search the documentation for the four listed terms referring to Central Frontend and review the surrounding usage. Choose and apply one consistent term where appropriate, then verify that the competing references have been resolved across the documentation.

Written by the indexing model from the issue text.