Update REST API links to use relative paths in index.yml and toc.yml

Author: Mukesh Dua

articles/microsoft-discovery/index.yml

@@ -115,4 +115,4 @@ landingContent:
       - linkListType: reference
         links:
           - text: REST API
-            url: https://learn.microsoft.com/rest/api/discovery/
+            url: /rest/api/discovery/

articles/microsoft-discovery/toc.yml

@@ -248,5 +248,5 @@ items:
         displayName: tutorial, Discovery Mode, first investigation, getting started
   - name: Reference
     items:
-      - name: REST API
-        href: https://learn.microsoft.com/rest/api/discovery/
+    - name: REST API
+      href: /rest/api/discovery/