doc: Update README.

Author: freezy

README.md

@@ -1,6 +1,15 @@
 # Pinball Assets
 
-*HDRP Assets for VPE.*
+This repo contains ready-to-use assets for the Visual Pinball Engine. They have been created following the guidelines documented [here](https://docs.visualpinball.org/creators-guide/editor/asset-library-styleguide.html).
+
+## Setup
+
+You'll need [git LFS](https://git-lfs.github.com/) in order to use this repo. [Install the extension](https://github.com/git-lfs/git-lfs/releases/download/v2.12.0/git-lfs-windows-v2.12.0.exe) if you don't already have. Then enable it before cloning the repo.
+
+```sh
+git lfs install
+git clone https://github.com/VisualPinball/VisualPinball.Unity.AssetLibrary.git
+```
 
 ## Credits