[Compendium] Link to academy

[stap-m]

I did not find a link to the academy in the compendium. I think it is important to prominently mention it as Family member and make it easy to navigate there.

[Ludee]

I added a sentence and link to this page:
https://openenergyplatform.github.io/organisation/family_community/knowledge_transfer/

I will also create a specific page under members