small rbac doc clarification

1. in ARM there is a table of role assignment methods would be cool to add example how to use remote-address (ip address has to be configured in name parameter, it wasn't in documentation so I was looking for something like ip-address parameter. Also custom-value for extension could use some additional statement.

2. Control agent global parameter cert-required has to be set to True if assign-role-method is based on TLS certs, ARM. from comment in example I would deduce that it can be False. Combination of global setting "cert-required": false, and hook setting "require-tls": true, won't work