docs: add missing deprecation docs (#3449)
docs: add missing deprecation docs (#3449)

Signed-off-by: Matt Klein <mklein@lyft.com>

Mirrored from https://github.com/envoyproxy/envoy @ 9db02a9c37a13f56d24ae10fc8e7e47539d47bf4

lyft/envoy-api,lyft/envoy-api,lyft/envoy-api