Update the prisma schema to reflect the most recent needs

[stephan418]

The schema should allow for:

• Adding roles to disciplines (with a schema describing the result)
• Storing results in the database
• Differentiation between campaigns and links (links are assigned to a specific group)
• Adding leaders to team (The person who receives join requests)
• Defining an optional description and (maybe) images to
  • Events and
  • Disciplines

Other requirements can and most likely will be added in the future, however, the outlined schema would be a solid baseline for future improvements.

Suggestions welcome

@Stefan-5422 @Flexla54 @michael5031

[stephan418]

The name of admins should maybe be unique?