Add a README.md with some basic documentation

README.md

@@ -0,0 +1,22 @@
+# LayerShellQt
+
+This component is meant for applications to be able to easily use clients based on wlr-layer-shell.
+
+What the protocol does is roughly explained in here: https://drewdevault.com/2018/07/29/Wayland-shells.html
+
+## Usage
+
+### CMake
+
+To use it from a CMake project you'll need to:
+```
+find_package(LayerShellQt REQUIRED)
+```
+
+Then it will offer us the target `LayerShellQt::Interface` that we can link to to get access to this framework.
+
+### C++
+
+You can use `LayerShellQt::Shell::useLayerShell();` to enable it before any clients are created.
+
+The class `LayerShellQt::Window` will give us access to surface-specific settings. We can get it by using `LayerShellQt::Window::get(window)` on whatever `QWindow` we need to tweak.