[doc] Fix anchor tags for error codes

doc/ws.md

@@ -45,17 +45,17 @@
   - [websocket.url](#websocketurl)
 - [WebSocket.createWebSocketStream(websocket[, options])](#websocketcreatewebsocketstreamwebsocket-options)
 - [WS Error Codes](#ws-error-codes)
-  - [WS_ERR_EXPECTED_FIN](#wserrexpectedfin)
-  - [WS_ERR_EXPECTED_MASK](#wserrexpectedmask)
-  - [WS_ERR_INVALID_CLOSE_CODE](#wserrinvalidclosecode)
-  - [WS_ERR_INVALID_CONTROL_PAYLOAD_LENGTH](#wserrinvalidcontrolpayloadlength)
-  - [WS_ERR_INVALID_OPCODE](#wserrinvalidopcode)
-  - [WS_ERR_INVALID_UTF8](#wserrinvalidutf8)
-  - [WS_ERR_UNEXPECTED_MASK](#wserrunexpectedmask)
-  - [WS_ERR_UNEXPECTED_RSV_1](#wserrunexpectedrsv1)
-  - [WS_ERR_UNEXPECTED_RSV_2_3](#wserrunexpectedrsv23)
-  - [WS_ERR_UNSUPPORTED_DATA_PAYLOAD_LENGTH](#wserrunsupporteddatapayloadlength)
-  - [WS_ERR_UNSUPPORTED_MESSAGE_LENGTH](#wserrunsupporteddatapayloadlength)
+  - [WS_ERR_EXPECTED_FIN](#ws_err_expected_fin)
+  - [WS_ERR_EXPECTED_MASK](#ws_err_expected_mask)
+  - [WS_ERR_INVALID_CLOSE_CODE](#ws_err_invalid_close_code)
+  - [WS_ERR_INVALID_CONTROL_PAYLOAD_LENGTH](#ws_err_invalid_control_payload_length)
+  - [WS_ERR_INVALID_OPCODE](#ws_err_invalid_opcode)
+  - [WS_ERR_INVALID_UTF8](#ws_err_invalid_utf8)
+  - [WS_ERR_UNEXPECTED_MASK](#ws_err_unexpected_mask)
+  - [WS_ERR_UNEXPECTED_RSV_1](#ws_err_unexpected_rsv_1)
+  - [WS_ERR_UNEXPECTED_RSV_2_3](#ws_err_unexpected_rsv_2_3)
+  - [WS_ERR_UNSUPPORTED_DATA_PAYLOAD_LENGTH](#ws_err_unsupported_data_payload_length)
+  - [WS_ERR_UNSUPPORTED_MESSAGE_LENGTH](#ws_err_unsupported_message_length)
 
 ## Class: WebSocket.Server