Update building-simple-cmdset-with-dialog-api.md (SharePoint#771)

The feature id (456da147-ced2-3036-b564-8dad5c1c2e34) seems to be the same as in the lab: "Deploy your extension to SharePoint (Hello world part 3)" (https://dev.office.com/sharepoint/docs/spfx/extensions/get-started/serving-your-extension-from-sharepoint).
The proposal is to change the last character to avoid the clash when performing all the labs.

Author: netash

docs/spfx/extensions/get-started/building-simple-cmdset-with-dialog-api.md

@@ -284,7 +284,7 @@ To ensure that our newly added **elements.xml** file is taken into account while
     "features": [{
       "title": "ListView Command Set - Deployment of custom action.",
       "description": "Deploys a custom action with ClientSideComponentId association",
-      "id": "456da147-ced2-3036-b564-8dad5c1c2e34",
+      "id": "456da147-ced2-3036-b564-8dad5c1c2e35",
       "version": "1.0.0.0",
       "assets": {        
         "elementManifests": [