Request: update docs and add support for rewarded interstitial ads for Equativ as ad source of mediation

[AndroidDeveloperLB]

trafficstars

They told me via email that they do support it, but sadly the docs and the Admob mediation console don't mention and allow to use it:

https://developers.google.com/admob/android/choose-networks https://developers.google.com/admob/android/mediation/equativ

Please talk with them and add it. Requested here too: https://groups.google.com/g/google-admob-ads-sdk/c/cxBzHwYZ1Uk