Icons: Update product icons + removed icon PNG files

Author: lamATnginx

exampleSite/content/_index.md

@@ -10,7 +10,7 @@ Documentation for hugo theme
     {{<card title="Test Product" titleUrl="/test-product/" icon="test-tubes"  isLanding="true">}}
       See explanations and usages of shortcodes
     {{</card >}}
-    {{<card title="NGINX Plus" titleUrl="/nginx/" brandIcon="NGINX-Plus-product-icon-RGB.svg"  isLanding="true">}}
+    {{<card title="NGINX Plus" titleUrl="/nginx/" brandIcon="NGINX-Plus-product-icon.svg"  isLanding="true">}}
       See a live example of theme components
     {{</card >}}
   {{</card-section>}}