release automation: gitea actions build every push and publish tagged releases (version from the tag, packages, sha256sums, changelog section as text), simple 5-step install guide in the readme

README.md

@@ -46,16 +46,35 @@ More pictures:
 
 ## Get it
 
-You need **your own copy of the game** (CD or ISO image). Development used the German CD; other
-language versions should work but are untested.
+You need **your own copy of the game** (the CD or an ISO image of it). Nothing else – LlamaMod
+brings everything it needs (also Java). Development used the German CD; other language versions
+should work but are untested.
 
-| System | Package | Start |
-|---|---|---|
-| Windows | `LlamaMod-<version>-full-windows-x64.zip` | unzip, start `LlamaMod.exe` (no installation, no admin rights) |
-| Linux | `LlamaMod-<version>-full-linux-x64.tar.gz` | unpack, start `./LlamaMod`; install **Wine** to run the game |
+### Install in 5 steps
 
-Both bring their own Java runtime; the editor needs OpenGL 3.3. A *launcher* edition without the
-editor is also built. What changed: [CHANGELOG.md](CHANGELOG.md).
+1. **Download** from the **Releases** page of this repository (top of the page):
+   * Windows: `LlamaMod-<version>-full-windows-x64.zip`
+   * Linux: `LlamaMod-<version>-full-linux-x64.tar.gz`
+
+   (*full* = with the level editor. The *launcher* packages are the same without the editor.)
+2. **Unpack** it into any folder you like (for example *Documents* or your home folder).
+   There is no installer and you need no admin rights.
+3. **Start** LlamaMod:
+   * Windows: double-click **`LlamaMod.exe`**. If Windows says *"Windows protected your PC"*,
+     click **More info → Run anyway** (the program is not signed, that's all).
+   * Linux: install Wine once (`sudo apt install wine` on Ubuntu/Mint/Debian), then double-click
+     **`LlamaMod`** or run `./LlamaMod`. `./install-desktop-entry.sh` adds it to your app menu.
+4. **Set up the game** – on the first start a short wizard asks for your game: put the CD in or
+   pick the ISO file, click **Set up** and wait about a minute. Your CD/ISO is only read, never
+   changed.
+5. **Play** – on the **Mods** tab tick the mods you want, click **Apply**, then **Play**.
+   *Restore original* switches all mods off again.
+
+New levels (Test World, Alligator Arena, Llama Coaster, your own) are in the hidden world
+**TestLevel**: open the **Save games** tab once and click **Unlock TestLevel**, then pick it on the
+world map. If your antivirus complains about `groove.exe`: mods that change the game program are
+marked *modifies groove.exe*; LlamaMod tells you what to do. More help:
+[Troubleshooting](docs/manual/20-troubleshooting.md). What changed: [CHANGELOG.md](CHANGELOG.md).
 
 ### Build from source