message: docs(techdocs): update readme with link to mkdocs readme
diff: @@ -4,6 +4,10 @@ Welcome to the TechDocs plugin - Spotify's docs-like-code approach built directl
  **WIP: This plugin is a work in progress. It is not ready for use yet. Follow our progress on [the Backstage Discord](https://discord.gg/MUpMjP2) under #docs-like-code or on [our GitHub Milestone](https://github.com/spotify/backstage/milestone/15).**
  +## Sections
  +
  +- [MkDocs](./mkdocs/README.md)
  +
  ## Getting started
  Your plugin has been added to the example app in this repository, meaning you'll be able to access it by running `yarn start` in the root directory, and then navigating to [/techdocs](http://localhost:3000/techdocs).
  