Add config json file template for ftd-api docs

docs/templates/static/ftd_api/config.json.j2

@@ -0,0 +1,37 @@
+{
+  "items": [
+    {
+      "title": "Overview",
+      "items": [
+        {
+          "title": "Introduction to Firepower Threat Defense REST API",
+          "content": "introduction/intro.md"
+        },
+        {
+          "title": "Authenticating Your REST API Client Using OAuth",
+          "content": "introduction/auth.md"
+        },
+        {
+          "title": "Deploying Configuration Changes",
+          "content": "introduction/deploy_config.md"
+        }
+      ]
+    },
+    {% if error_codes %}
+    {
+      "title": "Error Codes",
+      "content": "error_codes.md"
+    },
+    {% endif %}
+    {
+      "title": "Resources",
+      "type": "config",
+      "content": "resources/config.json"
+    },
+    {
+      "title": "Models",
+      "type": "config",
+      "content": "models/config.json"
+    }
+  ]
+}