[Documentation] Website doc update and annotated RFCs

You will need to update the apache documentation on how to configure and use the new `jmap` implementation: https://james.apache.org/server/config-jmap.html

You might need to create a new page, as we should keep the old doc for the versions of James implementing `jmap-draft`. You should as well redirect to proper JMAP RFCs (https://tools.ietf.org/html/rfc8620 and https://tools.ietf.org/html/rfc8621) and add annotated RFCs as part of `server/protocols/jmap-rfc-8621` folder.