Update docs.md

Fix:  style error

documentation20/en/00.index/docs.md

@@ -79,7 +79,7 @@ TDengine is a highly efficient platform to store, query, and analyze time-series
 - [Windows Client](https://www.taosdata.com/blog/2019/07/26/514.html): compile your own Windows client, which is required by various connectors on the Windows environment
 - [Rust Connector](/connector/rust): A taosc/RESTful API based TDengine client for Rust
 
-## [Components and Tools]
+## Components and Tools
 
 * [taosAdapter](/tools/adapter): a bridge/adapter between TDengine cluster and applications.
 * [TDinsight](/tools/insight): monitoring TDengine cluster with Grafana.