fixing natgw old hc location

otc_metadata/data/services.yaml

@@ -596,7 +596,7 @@ documents:
     service_type: mrs
     title: User Guide
     type: umn
-  - hc_location: api/natgw
+  - hc_location: api/nat
     html_location: docs/natgw/api-ref
     link: /nat-gateway/api-ref/
     pdf_name: natgw-api-ref
@@ -604,7 +604,7 @@ documents:
     service_type: natgw
     title: API Reference
     type: api-ref
-  - hc_location: usermanual/natgw
+  - hc_location: usermanual/nat
     html_location: docs/natgw/umn
     link: /nat-gateway/umn/
     pdf_name: natgw-umn