Clarify how local Keycloak enables reShapr OIDC user authentication

[yada]

dev/start-keycloak-docker.sh starts a local Keycloak instance for OIDC development, but the script output/comment could make it clearer that reShapr itself only uses this external IDP after the RESHAPR_AUTHENTICATION_IDP_* variables are enabled in the all-in-one Docker Compose file.

Suggested comment near the top of dev/start-keycloak-docker.sh:

# Starts local Keycloak only. To enable reShapr OIDC user authentication with this
# external IDP, set the RESHAPR_AUTHENTICATION_IDP_* vars in docker-compose-all-in-one.yml.
# The imported 3rdparty realm provides the reshapr-ctrl client and redirect URI.

This would reduce confusion between starting Keycloak and configuring reShapr to authenticate users through it.

[lbroudoux]

If we want to be comprehensive, we may also add a note on how to use this Keycloak and its realm when testing OAuth Elicitations too.

[yada]

Yes, and we now have a demo we can point to: https://github.com/reshaprio/reshapr-demos/tree/main/demos/09-open-meteo-openapi-keycloak-elicitation

I suggest we add this comment:

# Starts local Keycloak only. To enable reShapr OIDC user authentication with this
# external IDP, set the RESHAPR_AUTHENTICATION_IDP_* vars in docker-compose-all-in-one.yml.
#
# It also imports 3rd-party realm, the reshapr-ctrl client and redirect URIs for testing OAuth Elicitations with this Keycloak realm. 
# See demo: https://github.com/reshaprio/reshapr-demos/tree/main/demos/09-open-meteo-openapi-keycloak-elicitation