Explain manifest.json for the msteamsgen app

[mmattel]

WHAT Needs to be Documented?

The term manifest is used when using the msteamsgen app but it is not document what it is about. A brief description should be added. manifest.json is the apps main config file.

WHERE Does This Need To Be Documented (Link)?

https://doc.owncloud.com/server/admin_manual/configuration/integration/ms-teams.html#create-your-microsoft-teams-app

WHY Should This Change Be Made?

Clarify terms used

(Optional) What Type Of Content Change Is This?

• New Content Addition
• Old Content Deprecation
• Existing Content Simplification
• Bug Fix to Existing Content

(Optional) Which Manual Does This Relate To?

• Admin Manual
• Developer Manual
• User Manual
• Android
• iOS
• Branded Clients
• Desktop Client
• Other

See:
https://docs.microsoft.com/de-de/microsoftteams/platform/concepts/build-and-test/apps-package
https://docs.microsoft.com/de-de/microsoftteams/platform/resources/schema/manifest-schema

@tbsbdr as discussed