Add Example to README. Fixes issue #1.

Author: developit

README.md

@@ -6,6 +6,37 @@
 This is literally copied from the React 0.14 codebase.
 If you're using PropTypes with React, it would be silly to reference this standalone version.
 
-**LICENSE:** BSD.
+
+### Usage
+
+```js
+function check(props, propTypes) {
+	for (let prop in propTypes) {
+		if (propTypes.hasOwnProperty(prop)) {
+			let err = propTypes[prop](props, prop, 'name', 'prop');
+			if (err) {
+				console.warn(err);
+				return false;
+			}
+		}
+	}
+	return true;
+}
+
+let valid = check({
+  a: 42,
+  b: 'News'
+}, {
+  a: PropTypes.number,
+  b: PropTypes.oneOf(['News', 'Photos'])
+});
+
+valid;  // true
+```
+
+
+### License
+
+BSD
 
 [PropTypes]: https://github.com/facebook/react/blob/master/src/isomorphic/classic/types/ReactPropTypes.js