Use uri instead of url in source property of Image

Summary:
#13478 (comment)

Fix incorrect usage of `url` in the `source` property of `<Image />` in the example.
Closes #13496

Differential Revision: D4893299

Pulled By: hramos

fbshipit-source-id: 134f9100d16997627b14c145256818e05017bbe3

Author: mehcode

Examples/UIExplorer/js/ImageExample.js

@@ -656,7 +656,7 @@ exports.examples = [
         <View style={{flexDirection: 'row'}}>
           <Image
             source={{
-              url: 'ImageInBundle',
+              uri: 'ImageInBundle',
               bundle: 'UIExplorerBundle',
               width: 100,
               height: 100,
@@ -665,7 +665,7 @@ exports.examples = [
           />
           <Image
             source={{
-              url: 'ImageInAssetCatalog',
+              uri: 'ImageInAssetCatalog',
               bundle: 'UIExplorerBundle',
               width: 100,
               height: 100,