Add screenshot.

Author: CalebRas

Shared/Samples/Create dynamic basemap gallery/README.md

@@ -2,7 +2,7 @@
 
 Implement a basemap gallery that automatically retrieves the latest customization options from the basemap styles service.
 
-![screenshot](screenshot.png)
+![Screenshot of Create dynamic basemap gallery sample](create-dynamic-basemap-gallery.png)
 
 ## Use case
 

Shared/Samples/Create dynamic basemap gallery/README.metadata.json

@@ -2,7 +2,9 @@
     "category": "Maps",
     "description": "Implement a basemap gallery that automatically retrieves the latest customization options from the basemap styles service.",
     "ignore": false,
-    "images": [],
+    "images": [
+        "create-dynamic-basemap-gallery.png"
+    ],
     "keywords": [
         "basemap",
         "languages",