docs: add schemaless endpoint to rest api for cloud

docs/en/15-programming/01-connect/09-rest-api.md

 ---
-sidebar_label: REST API
-title: REST API
-description: Connect to TDengine Cloud Service through RESTful API 
+sidebar_label: REST and Schemaless
+title: REST and Schemaless
+description: Connect to TDengine Cloud Service through RESTful API or Schemaless
 ---
 
 <!-- exclude -->
@@ -50,3 +50,29 @@ curl -L \
   $TDENGINE_CLOUD_URL/rest/sql?token=$TDENGINE_CLOUD_TOKEN
 ```
 
+## Schemaless
+
+### InfluxDB Line Protocol
+
+You can use any client that supports the http protocol to access the RESTful interface address `http://<fqdn>:6041/influxdb/v1/write` to write data in InfluxDB compatible format to TDengine. The EndPoint is as follows:
+
+```text
+/influxdb/v1/write?db=<DB_NAME>&token=${TDENGINE_CLOUD_TOKEN}
+```
+
+Support InfluxDB query parameters as follows.
+
+- `db` Specifies the database name used by TDengine
+- `precision` The time precision used by TDengine
+
+Note: InfluxDB token authorization is not supported at present. Only Basic authorization and query parameter validation are supported.
+
+### OpenTSDB Json and Telnet Protocol
+
+You can use any client that supports the http protocol to access the RESTful interface address `http://<fqdn>:6041/opentsdb/v1/put` to write data in OpenTSDB compatible format to TDengine. The EndPoint is as follows:
+
+```text
+/opentsdb/v1/put/json/<db>?token=${TDENGINE_CLOUD_TOKEN}
+/opentsdb/v1/put/telnet/<db>?token=${TDENGINE_CLOUD_TOKEN}
+```
+