Add 'Configure Proxy Settings' link to index.yml

Author: ghogen

docs/ide/index.yml

@@ -69,6 +69,8 @@ landingContent:
             url: reference/command-prompt-powershell.md
           - text: Manage extensions
             url: finding-and-using-visual-studio-extensions.md
+          - text: Configure Proxy Settings
+            url: proxy-settings.md
 
   # Card
   - title: Develop in your language