Update index.yml

Update homepage

Author: kellydevens

articles/orbital/index.yml

@@ -25,6 +25,8 @@ landingContent:
         links:
           - text: Why use Azure Orbital Ground Station?
             url: overview.md
+          - text: Get started with Azure Orbital Ground Station
+            url: get-started.md
           - text: What is the Azure Space Partner Community?
             url: space-partner-program-overview.md