[skip ci] Add comment to embed etcd kv (#12003)

Signed-off-by: NEdward Zeng <jie.zeng@zilliz.com>

internal/kv/etcd/embed_etcd_kv.go

@@ -77,6 +77,7 @@ func (kv *EmbedEtcdKV) GetPath(key string) string {
 	return path.Join(kv.rootPath, key)
 }
 
+// LoadWithPrefix returns all the keys and values with the given key prefix
 func (kv *EmbedEtcdKV) LoadWithPrefix(key string) ([]string, []string, error) {
 	key = path.Join(kv.rootPath, key)
 	log.Debug("LoadWithPrefix ", zap.String("prefix", key))