Update `docs/content/administration/backup-and-restore.zh-cn.md`
`docs/content/contributing/guidelines-frontend.zh-cn.md`
`docs/content/help/support.zh-cn.md`
`docs/content/installation/database-preparation.zh-cn.md`
`docs/content/installation/windows-service.zh-cn.md`
`docs/content/usage/profile-readme.zh-cn.md` to be consistent with the
English document
This PR cleans up the docs in a way to make them simpler to ingest by
our [docs repo](https://gitea.com/gitea/gitea-docusaurus).
1. It includes all of the sed invocations our ingestion did, removing
the need to do it at build time.
2. It replaces the shortcode variable replacement method with
`@variable@` style, simply for easier sed invocations when required.
3. It removes unused files and moves the docs up a level as cleanup.
---------
Signed-off-by: jolheiser <john.olheiser@gmail.com>
