+ add sample readme

samples/hello-world/readme.txt

@@ -0,0 +1,25 @@
+======================
+== Hello World Demo ==
+======================
+
+1. MOTIVATION
+
+As the name implies, this is a simple demo that illustrates the configuration
+and interaction with the GemFire through the Spring container.
+
+The demo starts and configures the GemFire grid and open up a basic shell for
+executing commands against the grid.
+Multiple nodes can be started which will share and exchange information transparently.
+
+2. BUILD AND DEPLOYMENT
+
+This directory contains the source files.
+For building, Maven 2 and JDK 1.5+ are required.
+
+To build the sample, use the following command:
+
+# mvn clean package
+
+To run the sample, use:
+
+# mvn exec:java