Update README

Author: Jotschi

README

@@ -1 +1,16 @@
-Simple java implementation of a quadtree
+# JavaQuadTree
+
+Just a simple java implementation of a quadtree
+
+## Usage
+
+```
+PointQuadTree<String> tree = new PointQuadTree<String>(new Point(0, 0), new Dimension(600, 600));
+	tree.insert(1, 3, "1");
+	tree.insert(11, 32, "2");
+	tree.insert(11, 52, "3");
+	tree.insert(454, 555, "4");
+	tree.insert(353, 555, "5");
+	tree.insert(552, 555, "6");
+	tree.insert(551, 555, "7");
+```