This PR introduces the `ReviewedOn` and `ReviewedBy` variables for the
default merge message templates (e.g.,
`.gitea/default_merge_message/MERGE_TEMPLATE.md`).
This allows customizing the default merge messages while retaining these
trailers.
This also moves the associated logic out of `pull.tmpl` into the
relevant Go function.
This is a first contribution towards #11077.
---
For illustration, this allows to recreate the "default default" merge
message with the following template:
```
.gitea/default_merge_message/MERGE_TEMPLATE.md
Merge pull request '${PullRequestTitle}' (${PullRequestReference}) from ${HeadBranch} into ${BaseBranch}
${ReviewedOn}
${ReviewedBy}
```
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>
