Outdated Auth0 OIDC Docs

[matrixbot]

This issue has been migrated from #16753.

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Description:

The current docs for using Auth0 (snippet below) suggest using Rules to set user attributes, but Rules is being deprecated in favour of Actions. Docs on the migration can be found here.

New Auth0 users are unable to follow the docs as they are unable to create Rules. Existing users aren't yet affected.

function addPersistenceAttribute(user, context, callback) {
  user.user_metadata = user.user_metadata || {};
  user.user_metadata.preferred_username = user.user_metadata.preferred_username || user.user_id;
  context.idToken.preferred_username = user.user_metadata.preferred_username;

  auth0.users.updateUserMetadata(user.user_id, user.user_metadata)
    .then(function(){
        callback(null, user, context);
    })
    .catch(function(err){
        callback(err);
    });
}