Adds correct Zero Courses link (#1607)

Author: ZPain8464

content/docs/quickstart.mdx

@@ -127,7 +127,7 @@ You should land on the Verify page:
 
 :::info Build your own route
 
-Check out [**Pomerium Fundamentals: Build Routes**](/docs/courses/fundamentals/build-routes) to learn how to create a route to your own service behind Pomerium.
+Check out [**Pomerium Fundamentals: Build Routes**](/docs/courses/fundamentals/zero-build-routes) to learn how to create a route to your own service behind Pomerium.
 
 :::