doc: refine index of connect and connectors

docs/en/15-programming/01-connect/index.md

+---
+sidebar_label: Connect
+title: Connect to TDengine Cloud Service
+description: Quick start of using TDengine connectors to conenct
+---
+
+This section briefly describes how to connect to TDengine cloud service using the connectors provided by TDengine so that programmers can get started quickly.
+
+```mdx-code-block
+import DocCardList from '@theme/DocCardList';
+import {useCurrentSidebarCategory} from '@docusaurus/theme-common';
+
+<DocCardList items={useCurrentSidebarCategory().items}/>
+```

docs/en/15-programming/03-connector/index.md

-# Connector 
+---
+sidebar_label: Connector
+title: Connector Reference
+description: Reference guide for connectors
 
+This section is a detailed reference guide of the connectors provided by TDengine.
 
 ```mdx-code-block
 import DocCardList from '@theme/DocCardList';