Readme update

README.md

@@ -1,6 +1,6 @@
 # Matrix8 Library
 
-LED 8x8 Matrix via shift registers.
+## LED 8x8 Matrix via shift registers.
 
 ![8x8 matrix](https://frogling.com/site/wp-content/uploads/2018/06/DSC_0932.jpg)
 
@@ -10,7 +10,43 @@ This library control LED 8x8 matrix via two shift registers (for example 74HC595
 
 * Download all repo files
 * Go to arduino IDE root
-* Copy all files to library/Matrix8
+* Copy all files to `library/Matrix8`
 * Just use!
 
-## TODO: examples and documentation
+## Simple example
+
+Drawing cross
+
+```cpp
+#include "matrix8.h"
+
+// Init matrix8
+//   latch - 7
+//   clock - 6
+//   data  - 8
+Matrix8 matrix(7, 6, 8);
+
+void setup() {
+  // Creating two diagonal lines (cross)
+  for (int i = 0; i < 8; i++) {
+    matrix.set(i, i, true);
+    matrix.set(i, 7 - i, true);
+  }
+}
+
+void loop() {
+  // Loop draw
+  matrix.draw();
+}
+```
+
+![8x8 matrix cross](https://frogling.com/site/wp-content/uploads/2018/06/p2212.jpg)
+
+## Functions
+
+* `Matrix8(latch, clock, data)` - init matrix8 constructor
+* `Matrix8(latch, clock, data, point to byte buffer)` - init matrix8 with external buffer
+* `set(x, y, value)` - set segment value by position
+* `draw()` - draw row by row matrix
+* `draw(delay)` - draw with delay after rows print, just for test
+* `clear()`  - clear matrix buffer