transport sockets: expose proxy protocol socket (#12762)

Signed-off-by: Weston Carlson <wez470@gmail.com>

Mirrored from https://github.com/envoyproxy/envoy @ b18f57e265a172cb0ae324acc67861c2f8a101f3

envoy/extensions/transport_sockets/proxy_protocol/v3/upstream_proxy_protocol.proto

@@ -6,7 +6,6 @@ import "envoy/config/core/v3/base.proto";
 import "envoy/config/core/v3/proxy_protocol.proto";
 
 import "udpa/annotations/status.proto";
-import "udpa/annotations/versioning.proto";
 import "validate/validate.proto";
 
 option java_package = "io.envoyproxy.envoy.extensions.transport_sockets.proxy_protocol.v3";
@@ -16,9 +15,10 @@ option (udpa.annotations.file_status).package_version_status = ACTIVE;
 
 // [#protodoc-title: Upstream Proxy Protocol]
 // [#extension: envoy.transport_sockets.upstream_proxy_protocol]
-// [#not-implemented-hide:]
+
 // Configuration for PROXY protocol socket
 message ProxyProtocolUpstreamTransport {
+  // The PROXY protocol settings
   config.core.v3.ProxyProtocolConfig config = 1;
 
   // The underlying transport socket being wrapped.