fixed TOC link

Author: Ryan Willis

articles/azure-arc/servers/toc.yml

@@ -167,8 +167,8 @@
       href: azcmagent-connect.md
     - name: azcmagent disconnect
       href: azcmagent-disconnect.md
-    - name: azcmagent-extension.md
-      href: azcmagent extension
+    - name: azcmagent extension
+      href: azcmagent-extension.md
     - name: azcmagent genkey
       href: azcmagent-genkey.md
     - name: azcmagent help