added 'Tech Specs' section under API Gateway

website/content/docs/api-gateway/api-gateway-tech-specs.mdx

@@ -0,0 +1,8 @@
+---
+layout: docs
+page_title: Consul API Gateway Technical Specifications
+description: >-
+    This topic describes technical specifications for Consul API Gateway.
+---
+
+# Technical Specifications

website/content/docs/api-gateway/api-gateway.mdx

@@ -1,7 +1,8 @@
 ---
 layout: docs
 page_title: API Gateway
-description: Using Consul API gateway functionality
+description:  >-
+  Using Consul API gateway functionality
 ---
 
 # Consul API Gateway

website/data/docs-nav-data.json

@@ -373,10 +373,19 @@
         "hidden": true
       }
     ]
-  },
+  },  
   {
-    "title": "Consul API Gateway <sup>BETA</sup>",
-    "path": "api-gateway"
+    "title": "Consul API Gateway",
+    "routes": [
+      {
+        "title": "Consul API Gateway",
+        "path": "api-gateway/api-gateway"
+      },
+      {
+        "title": "Technical Specifications",
+        "path": "api-gateway/api-gateway-tech-specs"
+      }      
+    ]
   },
   {
     "title": "Kubernetes",