API: Update Team entity over API

[baierjan]

Description of the enhancement request

Would be nice to have a method to update Team entity over API. Sometimes a display name or public description for a team changes and it would be nice to be able to update it programmatically. I would image a PUT endpoint as already implemented for other entities like for Groups in #2383.

Expected behaviour

curl -X PUT /api/v4/contests/demo/teams/teamid --json '{"id": "teamid", "name": "My team", "public_description": "New description"}'

[baierjan]

I am not sure if that is intentional, I just found out that doing a POST against /api/v4/teams with already existing ID will actually update it. So it behaves completely different from endpoints like /api/v4/users or /api/v4/contests/demo/groups. If this is intentional, it would be nice to update the API documentation to explicitly state it allows entity updates.