Example deployments for authelia and authentik

The desktop client recently received a couple of bug reports regarding two new(?) IdPs called [authelia](https://github.com/authelia/authelia) and [authentik](https://goauthentik.io/). These appear to be easier to set up than Keycloak.

I think the server should add example deployments for both of them like it is done with Keycloak to:

a) allow for easier debugging against either of these
b) make it easier for users to deploy their oCIS instances correctly against either of these

CC @michaelstingl, @TheOneRing