[gitea] Add readme with build and install instructions

alpine/gitea/README.md

@@ -0,0 +1,35 @@
+# Gitea: Git with a cup of tea
+
+Gitea seems like a good candidate for a selfhosted variant of GitHub, so why
+not host it in a squashfs image ... :)
+
+Add `app.ini` in `/etc/gitea` on the host you'll run Gitea.
+
+To build the image run `build.sh` and that should be it.
+
+## Installation
+
+Gitea has a web UI installer to set up the database and the filesystem
+structure. Couldn't find a cli that does it, it's a bit cumbersome to do it
+through the web UI, but here goes.
+
+1. Comment the `INSTALL_LOCK   = true` variable in /etc/gitea/app.ini, or set
+   it to `false`.
+
+2. Open http://localhost:3000/install and set all configuration to match the
+   one in /etc/gitea/app.ini. The image below matches the config from this
+   repo.
+
+   ![Installation main screen](img/install.png)
+
+   You will get an error:
+
+   ```
+   Failed to save configuration: open /etc/gitea/app.ini: permission denied
+   ```
+
+3. Profit! The filesystem and db are all set up, you can ignore the permission
+   error.
+
+4. **YOU'LL NEED TO UPDATE** `INSTALL_LOCK = true` in app.ini to continue using
+   Gitea without being redirected to /install.