chore: add license header (#35)

Signed-off-by: Ruihang Xia <waynestxia@gmail.com>

proto/greptime/v1/health.proto

@@ -1,3 +1,17 @@
+// Copyright 2023 Greptime Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 syntax = "proto3";
 
 package greptime.v1;
@@ -6,7 +20,6 @@ option java_package = "io.greptime.v1";
 option java_outer_classname = "Health";
 option go_package = "github.com/GreptimeTeam/greptime-proto/go/greptime/v1";
 
-
 service HealthCheck {
   rpc HealthCheck(HealthCheckRequest) returns (HealthCheckResponse);
 }