Added the /clusters?format=json admin endpoint along with a proto representation of /clusters.
Risk Level: Low
Testing: Added a unit test for the new format.
Docs Changes: Added a brief description on the admin docs and linked to the more detailed proto definition.
Release Notes: Added release notes.
Fixes#2020
Signed-off-by: Matt Rice <mattrice@google.com>
Mirrored from https://github.com/envoyproxy/envoy @ 64605338ef040a949c5ea205bdd472a8fe42306c
data-plane-api(CircleCI)