chore: add license header (#35)

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

proto/greptime/v1/meta/cluster.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.meta;
@@ -8,7 +22,7 @@ import "greptime/v1/meta/store.proto";
 
 // Cluster service is used for communication between meta nodes.
 service Cluster {
-  // Batch get kvs by input keys from leader's in_memory kv store. 
+  // Batch get kvs by input keys from leader's in_memory kv store.
   rpc BatchGet(BatchGetRequest) returns (BatchGetResponse);
 
   // Range get the kvs from leader's in_memory kv store.