chore: Updates GCP API description

Corrects the API description to accurately reflect that it is a GCP API, not an Azure API.

Author: davemooreuws

docs/providers/pulumi/gcp.mdx

@@ -134,7 +134,7 @@ apis:
   # Target an API by its nitric name
   my-api:
     # provide domains to be used for the api
-    description: An Azure API
+    description: A GCP API
 
 # Add CDN configuration, required for websites deployments
 # Available since v1.20.0