Update docs with settings for OIDC prefix.
https://docs.allauth.org/en/latest/release-notes/recent.html#backwards-incompatible-changes
In version 0.60 of allauth, the OIDC login url has been changed. Either the URL's in Keycloak need updating, or we need to set for each app the prefix to SOCIALACCOUNT_OPENID_CONNECT_URL_PREFIX = ""
instead.