Added FAQ section to TOC

Author: vpattnai

defender-xdr/TOC.yml

@@ -338,6 +338,8 @@
             href: access-den-graph-api.md
           - name: Ask Defender Experts
             href: experts-on-demand.md
+        - name: Frequently asked questions
+          href: faq-defender-experts-hunting.md    
         - name: Understand Defender Experts for Hunting reports
           href: defender-experts-report.md
       - name: Collaborate with Microsoft Defender Experts for XDR