Docusaurus-ify (#26051)

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>

docs/content/administration/git-lfs-support.en-us.md

@@ -0,0 +1,32 @@
+---
+date: "2019-10-06T08:00:00+05:00"
+title: "Git LFS setup"
+slug: "git-lfs-setup"
+sidebar_position: 12
+toc: false
+draft: false
+aliases:
+  - /en-us/git-lfs-setup
+menu:
+  sidebar:
+    parent: "administration"
+    name: "Git LFS setup"
+    sidebar_position: 12
+    identifier: "git-lfs-setup"
+---
+
+# Git Large File Storage setup
+
+To use Gitea's built-in LFS support, you must update the `app.ini` file:
+
+```ini
+[server]
+; Enables git-lfs support. true or false, default is false.
+LFS_START_SERVER = true
+
+[lfs]
+; Where your lfs files reside, default is data/lfs.
+PATH = /home/gitea/data/lfs
+```
+
+**Note**: LFS server support needs at least Git v2.1.2 installed on the server