Update README.md

Author: TDHolmes

README.md

@@ -1,6 +1,26 @@
 # Control RGB LED displays from Rust
 
-This repository contains rust bindings for [rpi-rgb-led-matrix](https://github.com/hzeller/rpi-rgb-led-matrix).
+This repository contains rust bindings for the C++ library [rpi-rgb-led-matrix](https://github.com/hzeller/rpi-rgb-led-matrix),
+which enables controlling Hub75 based displays.
 In order to take advantage of the newer APIs, the minimum supported commit of the library is
 [55fa32f](https://github.com/hzeller/rpi-rgb-led-matrix/commit/55fa32fc2e02afb254ac834aea93589d5b891a11)
 (Sept. 7th, 2020), which exposes all parameters that affect how the matrix runs.
+
+# Usage
+
+The examples have more detailed usage, but here is basic usage to get things rendering on your display.
+```rust
+use rpi_led_matrix::{LedMatrix, LedColor};
+
+let matrix = LedMatrix::new(None, None).unwrap();
+let mut canvas = matrix.offscreen_canvas();
+for red in 0..255 {
+    for green in 0..255 {
+        for blue in 0..255 {
+            canvas.fill(&LedColor { red, green, blue });
+            canvas = matrix.swap(canvas);
+        }
+    }
+}
+```
+Note that if you have wirings other than the libraries "default", you will need to construct arguments to the library to specify the layout. See `LedMatrixOptions` for more information.