update docs

Signed-off-by: NAnnie_wang <annie.wangli@huawei.com>

en/application-dev/connectivity/Readme-EN.md

 # Connectivity
 
 - Network Management
-    - [Network Management Overview](net-mgmt-overview.md)
-    - [HTTP Data Request](http-request.md)
-    - [WebSocket Connection](websocket-connection.md)
-    - [Socket Connection](socket-connection.md)
+  - [Network Management Overview](net-mgmt-overview.md)
+  - [HTTP Data Request](http-request.md)
+  - [WebSocket Connection](websocket-connection.md)
+  - [Socket Connection](socket-connection.md)
 - IPC & RPC
-    - [IPC & RPC Overview](ipc-rpc-overview.md)
-    - [IPC & RPC Development](ipc-rpc-development-guideline.md)
-    - [Subscribing to State Changes of a Remote Object](subscribe-remote-state.md)
+  - [IPC & RPC Overview](ipc-rpc-overview.md)
+  - [IPC & RPC Development](ipc-rpc-development-guideline.md)
+  - [Subscribing to State Changes of a Remote Object](subscribe-remote-state.md)

en/application-dev/reference/errorcodes/errorcode-buffer.md

+# Buffer Error Codes
+
+## 10200001 Value Out of Range
+
+**Error Message**
+
+The value of ${param} is out of range.
+
+**Description**
+
+The value of a parameter passed in the API exceeds the valid range.
+
+**Possible Causes**
+
+The parameter value exceeds the value range.
+
+**Solution**
+
+Check and modify the parameter value.
+
+## 10200009 Incorrect Buffer Size
+
+**Error Message**
+
+Buffer size must be a multiple of ${size}
+
+**Description**
+
+The buffer size must be an integer multiple of 16 bits, 32 bits, or 64 bits.
+
+**Possible Causes**
+
+The buffer size is not an integer multiple of 16 bits, 32 bits, or 64 bits.
+
+**Solution**
+
+Check the buffer length.
+
+## 10200013 Read-Only Properly
+
+**Error Message**
+
+Cannot set property ${propertyName} of Buffer which has only a getter.
+
+**Description**
+
+The buffer ${propertyName} is read-only and cannot be set.
+
+**Possible Causes**
+
+The ${propertyName} parameter is read-only and cannot be set.
+
+**Solution**
+
+${propertyName} cannot be set. Do not place it on the left of the equal sign (=).