Add descriptor for resource allocation tables

Also fix typo under TCP Ports Required

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

@@ -32,6 +32,8 @@ Supported version of the Gateway API spec: v1alpha2
 
 ## Resource Allocations
 
+The tables below list the resource allocations for each component of the API Gateway.
+
 ### Gateway Controller Pod
 
 | Resource | Allocation                                                                                               |
@@ -48,7 +50,7 @@ Supported version of the Gateway API spec: v1alpha2
 
 ## TCP Ports Required
 
-The tables below lists the TCP ports that are used by each component of the API Gateway.
+The tables below list the TCP ports that are used by each component of the API Gateway.
 
 ### Gateway Controller Pod