TOC: covert docs-cn to DITA TOC (#1242)
TOC: covert docs-cn to DITA TOC (#1242)

* TOC: covert docs-cn to DITA TOC

* TOC: update wording

* TOC: refine wording

* toc: update description and a link

* toc: update wording

* toc: update a file name

* toc: remove the K8s link

* toc: fix a link about incremental replication

* toc: update a blog post link to Chinese version

* toc: fix a link and update wording

* toc: update key features and overview

* toc: update About TiDB

pingcap/docs-cn,pingcap/docs-cn