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

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

docs/learn/tests/helpers.bash

@@ -40,6 +40,7 @@ setup_example_sandbox() {
   git -C "$DAGGER_SANDBOX" clone https://github.com/dagger/examples
 
   export DAGGER_SANDBOX="$DAGGER_SANDBOX"/examples/todoapp
+  dagger --project "$DAGGER_SANDBOX" init
 }
 
 
@@ -91,4 +92,4 @@ skip_unless_local_kube() {
     else
         skip "local kubernetes cluster not available"
     fi
-}
+}