Base Layer documentation is not comprehensive enough

[aeduard]

It is not clear how to add base layers other than OpenStreet, OpenTopo and IGN Ortho for newer versions of Lizmap (currently using 3.8).
The documentation (version 3.8 and 3.9) has a screenshot from an older version of the plugin, for sure pre 3.7 where you could put your API key from the provider and select the type of the baselayer (Satellite, Hybrid etc). Now the Base-layers tab does have this option but it is unavailable for newer server versions.

As for the Google Satellite imagery products there are no longer available for European Economic Area customers (maybe it should be also mentioned in the documentation), I've tried to migrate to Bing/Azure maps. I've obtained a key but simply adding to lizmap plugin does not work. In the past it worked with QuickMapServices plugin, but it doesn't anymore. Should I add an XYZ Tile into baselayers group? For Bing it means it should have the API key already in the connection link, so it will not use the key copied into the Lizmap plugin.

Right now I think it is not clear how to add a basemap which uses an API key, an update to the documentation would be welcome.