Converted images from SVG to PNG, updated articles

O365-CDN-flow-transparent.png already existed in the media folder

Author: kelleyvice-msft

microsoft-365/enterprise/content-delivery-networks.md

@@ -59,7 +59,7 @@ The built-in Microsoft 365 Content Delivery Network (CDN) allows Microsoft 365 a
 
 The Microsoft 365 CDN is composed of multiple CDNs that allow you to host static assets in multiple locations, or _origins_, and serve them from global high-speed networks. 
 
-![Microsoft 365 CDN conceptual diagram.](../media/O365-CDN/o365-cdn-flow-transparent.svg "Microsoft 365 CDN conceptual diagram")
+![Microsoft 365 CDN conceptual diagram.](../media/O365-CDN/o365-cdn-flow-transparent.png "Microsoft 365 CDN conceptual diagram")
 
 Content in **public** origins within the Microsoft 365 CDN is accessible anonymously, and can be accessed by anyone who has URLs to hosted assets. Because access to content in public origins is anonymous, you should only use them to cache non-sensitive generic content such as JavaScript files, scripts, icons and images. The Microsoft 365 CDN is used by default for downloading generic resource assets like the Microsoft 365 client applications from a public origin.
 

microsoft-365/enterprise/microsoft-365-overview.md

@@ -118,7 +118,7 @@ For more information and configuration examples for a small and medium business
 
 ## Microsoft 365 training
 
-![Microsoft 365 Fundamentals training.](../media/microsoft-365-overview/m365-fundamentals.svg)
+![Microsoft 365 Fundamentals training.](../media/microsoft-365-overview/m365-fundamentals.png)
 
 To learn more about Microsoft 365 and work toward a Microsoft 365 certification, you can start with [Microsoft 365 Fundamentals](/training/courses/ms-900t01/).