feat(output): cnosdb_subscription plugin add cnosdbv2.3 support

Author: zipper-meng

plugins/inputs/cnosdb_subscription/README.md

@@ -1,21 +1,31 @@
 # CnosDB Subscription Input Plugin
 
-## Build
+## Usages
 
-To compile this plugin it requires protoc-gen-go and protoc-gen-go-grpc
+To listen on port 8803:
 
-```shell
-# install protoc-gen-go
-go install google.golang.org/protobuf/cmd/protoc-gen-go@latest
-# install protoc-gen-go-grpc
-go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest
+```toml
+[[inputs.cnosdb_subscription]]
+service_address = ":8803"
 ```
 
-## Usages
-
-To listen on port 8803:
+If you want to get response from output plugins immediately, add config `high_priority_io = true`:
 
 ```toml
 [[inputs.cnosdb_subscription]]
 service_address = ":8803"
+high_priority_io = true
+```
+
+## Develop
+
+If you want to edit protocol files (in directory `protocol/`),
+you need **protoc-gen-go** and **protoc-gen-go-grpc** to re-compile them.
+See [generate.go](./generate.go).
+
+```shell
+# install protoc-gen-go
+go install google.golang.org/protobuf/cmd/protoc-gen-go@latest
+# install protoc-gen-go-grpc
+go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest
 ```