Ah I see what I did. This is user error 🙂 I searched using keywords Azure Subnet in the search the docs field which lead me to:
/Docs/Reference/API/Azure/network/Subnet
So me being new and not knowing there were two providers simply got confused. My apologies. This was user error. I should probably just use the links rather than the built-in search for the page
https://www.pulumi.com/docs/reference/pkg/azure/network/subnet/