xos-sample-gui-extension cleanup and update with new documentation

Change-Id: I6b70f5127ea631cfdd1f8a372a51c20f547e9c44
diff --git a/src/index.ts b/src/index.ts
index dad4a74..f1b6323 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -57,7 +57,7 @@
     );
 
     XosKeyboardShortcut.registerKeyBinding({
-        key: 'd',
+        key: 'p',
         description: 'Alert popup',
         cb: () => {
           alert('This binding is provided by the "xos-sample-gui-extension"');