grpc descriptor out for envoy.md

from local machine

git clone https://github.com/envoyproxy/data-plane-api
cd data-plane-api
bazel build //...
protoc \
   -I bazel-data-plane-api/external/googleapis/google/rpc/ \
   -I bazel-data-plane-api/external/com_lyft_protoc_gen_validate/ \
   -I . \
   --include_imports \
   --descriptor_set_out /tmp/ads.fds \
   envoy/service/discovery/v2/ads.proto
   
protoc \
   -I bazel-data-plane-api/external/googleapis \
   -I bazel-data-plane-api/external/com_lyft_protoc_gen_validate/ \
   -I . \
   --include_imports \
   --descriptor_set_out /tmp/cds.fds \
   envoy/api/v2/cds.proto   

protoc \
   -I bazel-data-plane-api/external/googleapis \
   -I bazel-data-plane-api/external/com_lyft_protoc_gen_validate/ \
   -I . \
   --include_imports \
   --descriptor_set_out /tmp/lds.fds \
   envoy/api/v2/lds.proto   

GOOS=linux go build -o /tmp/grpcurl ~/go/src/github.com/fullstorydev/grpcurl/cmd/

bosh scp /tmp/cds.fds istio-control/0:/tmp/cds.fds
bosh scp /tmp/lds.fds istio-control/0:/tmp/lds.fds
bosh scp /tmp/grpcurl istio-control/0:/tmp/

from BOSH VM

grpcurl -protoset /tmp/lds.fds describe

grpcurl -plaintext -protoset /tmp/lds.fds localhost:15010 envoy.api.v2.ListenerDiscoveryService/StreamListeners

currently returns

ERROR:
  Code: Unimplemented
  Message: unknown service envoy.api.v2.ListenerDiscoveryService