Add cloud services branch

For meanwhile integrated cloud services, we should have a stable place for documentation. So far, stubs of documentation were collected in SI working group sub-sub-folders.

Proposal:

• Add a "Helmholtz Cloud Service Documentation" folder -- (source)
  • Have subdirectories for each service. Service name MUST be equal to the one in cloud portal / Service DB.
  • all integrated/documented services will then be located at
    https://hifis.net/doc/cloud-services/<service-name>_<service-provider>
• Rename "Service Integration/Services" to "Service Integration/SI Working Groups" (025c2619)
• Applied example for
  • Nubes
    • with AAI integration moved from SI subfolder (62ab5be0)
  • bwSync&Share (ongoing work in !141 (merged))