Move XDS_PROTOCOL.md into sphinx docs #6338
Description
https://github.com/envoyproxy/envoy/blob/master/api/XDS_PROTOCOL.md
We should port this into the sphinx docs. It will be more discoverable, allow direct ref linking, etc.
{{ message }}
https://github.com/envoyproxy/envoy/blob/master/api/XDS_PROTOCOL.md
We should port this into the sphinx docs. It will be more discoverable, allow direct ref linking, etc.