Backport #24979
Changes:
1. Use uniform links types relative to doc folder (start with `doc/`)
2. According to [docusaurus
links](https://docusaurus.io/docs/markdown-features/links), if `<a>` is
used, the `href` is resolved as URL location, but not file location. So
need to use `[text]({{< relref "path" >}})` instead.
(cherry picked from commit d2c9fb02dd)
