docs: added abililty to run a local registry for todoapp example

Signed-off-by: Sam Alba <sam.alba@gmail.com>

docs/learn/tests/getting-started/plans/local/local.cue

@@ -5,15 +5,29 @@ import (
 	"alpha.dagger.io/docker"
 )
 
+// docker local socket
+dockerSocket: dagger.#Stream & dagger.#Input
+
 // run our todoapp in our local Docker engine
 run: docker.#Run & {
 	ref:  push.ref
 	name: "todoapp"
 	ports: ["8080:80"]
-	socket: dagger.#Stream & dagger.#Input
+	socket: dockerSocket
+}
+
+// run our local registry
+registry: docker.#Run & {
+	ref:  "registry:2"
+	name: "registry-local"
+	ports: ["5000:5000"]
+	socket: dockerSocket
 }
 
 // push to our local registry
 // this concrete value satisfies the string constraint
 // we defined in the previous file
 push: target: "localhost:5000/todoapp"
+
+// output the application URL
+appURL: "http://localhost:8080/" & dagger.#Output