Add meta image for Nexxiot case study and include image file (#14861)

Author: adamgordonbell

content/case-studies/nexxiot.md

@@ -4,6 +4,7 @@ title: "Nexxiot: Infrastructure Management for IoT Operations"
 description: |
     Nexxiot adopted Pulumi to streamline cloud infrastructure management, removing the burden of maintaining custom tooling while achieving zero infrastructure-related outages.
 meta_desc: Learn how Nexxiot worked with Pulumi to transform their infrastructure management, saving engineering resources and improving reliability.
+meta_image: "/images/case-studies/nexxiot.png"
 
 customer_name: Nexxiot
 customer_logo: /logos/customers/nexxiot.svg