added documentation for simply.keyboard

docs/simply.keyboard.md

@@ -0,0 +1,60 @@
+# simply.keyboard
+
+simply.keyboard is a simple library to add keyboard support to your application:
+
+```javascript
+let myKeys = {
+  default: {
+    ArrowDown: (e) => {
+      // handle arrow down
+    }
+  }
+}
+simply.keyboard(myApp, myKeys);
+```
+
+But generally you won't use this directly, but through simply.app:
+
+```javascript
+var myApp = simply.app({
+  keyboard: {
+    default: {
+      ArrowDown: (e) => {
+
+      }
+    }
+  }
+});
+```
+
+You can add multiple keyboard definitions:
+
+```javascript
+var counterApp = simply.app({
+  keyboard: {
+    default: {
+      ArrowDown: (e) => {
+
+      }
+    },
+    alternate: {
+      ArrowDown: (e) => {
+
+      }
+    }
+  }
+});
+```
+
+The default keyboard is 'default', but you can switch the keyboard by setting this attribute:
+
+```html
+<div data-simply-keyboard="alternate">
+  <input type="text" name="example">
+</div>
+```
+
+Whenever a keyboard `keydown` is fired, simply.keyboard will look for the closest parent with a `data-simply-keyboard` attribute. If found, it will use that keyboard definition. If not found, it will use `default`.
+
+The `keydown` event is only handled if the activeElement (the element that has focus) is inside the application container. See `simply.app` for more on that.
+