Allow developers to add this as a service to their Docker Compose file to enable local OAuth 2.0 flows.
See the following example:
```
services:
oauth2:
build: https://gitea.dsv.su.se/DMC/oauth2-authorization-server.git
restart: unless-stopped
ports:
- "<host_port>:8080"
environment:
CLIENT_ID=awesome-app
CLIENT_SECRET=p4ssw0rd
CLIENT_REDIRECT_URI=http://localhost/oauth2/callback
```
Reviewed-on: #1
