add a Button to add a gate via Frontend

[IngmarStempellConsid]

Feature Description

There is a button on a fresh "Gates" Installation, which adds a group, service and environment. This button is there so the user does not need to make an HTTP Request with a tool

Benefit

More easy to use

Additional Context

If you have a fresh installation of gates - you can not do anything with the frontend. A Button with a textarea for the name of the service would be a great help. At least a README page would be a great success.