Improve README and fix markdownlint warnings

README.md

@@ -1,27 +1,28 @@
-![Screenshot of TPS demo](screenshot.png)
+# Third Person Shooter Demo
 
-## Third Person Shooter Demo
+![Screenshot of TPS demo](screenshot.png)
 
 Third person shooter demo made using [Godot Engine](https://godotengine.org) 3.1.
 
-Note: Until Godot 3.1-stable is released, you need a recent build from Godot's
+**Note:** Until Godot 3.1-stable is released, you need a recent build from Godot's
 *master* branch to run this demo. You can build the engine from source, or use one
 of @Calinou's [nightly builds](https://hugo.pro/projects/godot-builds).
 
-Note 2: The repository is big and asset importing not well optimized yet, so expect
+**Note 2:** The repository is big and asset importing not well optimized yet, so expect
 a high CPU and RAM load when opening the project for the first time.
 
-### Git LFS
+## Git LFS
 
 This demo uses [Git LFS](https://git-lfs.github.com/) to store the heaviest assets.
 
 You need to install Git LFS on your system, and then fetch the assets from the LFS
 repository with:
-```
+
+```text
 git lfs fetch
 git checkout master
 ```
 
-### License
+## License
 
-See [LICENSE.txt] for details.
+See [LICENSE.txt](/LICENSE.txt) for details.