Add serverless guide with function template example: hamiltonian simulation

docs/guides/_toc.json

@@ -508,6 +508,10 @@
             {
               "title": "Port code to Qiskit Serverless",
               "url": "/guides/serverless-port-code"
+            },
+            {
+              "title": "Build a Function template that performs hamiltonian simulation",
+              "url": "/guides/serverless-hamsim-template"
             }
           ]
         },