Enrich Service Descriptions with link to useful materials/tutorials

Derived from https://gitlab.hzdr.de/hifis/overall/hifis.net/-/issues/204.

For several cloud services, there is additional information / tutorials / learning material etc available that should be linked in the service description, so that users can find.

In the comments, we can collect specific links for specific services and add them to the actual SD, when appropriate.

---

User Stories:

• As a user, I want to find additional information on the service I click on, in order to assess the applicability of the service for my purposes, and maximize the benefit for me.
• As service provider, I want to provide useful information to my users, in order to have them use my service appropriately and minimize first level support contacts.