added proxy example

src/learn/simple_proxy/Proxy.java

@@ -0,0 +1,11 @@
+package learn.simple_proxy;
+
+public class Proxy implements Subject {
+    private RealSubject realSubject = new RealSubject();
+
+    @Override
+    public void request() {
+        System.out.println("Proxy does some preliminary job and checks");
+        realSubject.request();
+    }
+}