Update pulumi-stacks.md

A little example how the stack and stacks work together

Author: Jeroendevr

content/docs/esc/integrations/infrastructure/pulumi-iac/pulumi-stacks.md

@@ -30,11 +30,26 @@ values:
     privateSubnetIds: ${stackRefs.vpcInfra.privateSubnetIds}
 ```
 
+Where your stack file is for e.g.
+```py
+# __main__.py
+import pulumi
+import pulumi_awsx as awsx
+
+# Fetch the default VPC for the current AWS region.
+vpc = awsx.ec2.DefaultVpc("default-vpc")
+
+# Export a few properties to make them easy to use.
+pulumi.export("vpcId", vpc.vpc_id)
+pulumi.export("publicSubnetIds", vpc.public_subnet_ids)
+pulumi.export("privateSubnetIds", vpc.private_subnet_ids)
+```
+
 ## Inputs
 
-| Property | Type                                   | Description                                   |
-|----------|----------------------------------------|-----------------------------------------------|
-| `stacks` | map[string][PulumiStack](#pulumistack) | A map of names to stacks to get outputs from. |
+| Property | Type                                   | Description                                                                                 |
+|----------|----------------------------------------|---------------------------------------------------------------------------------------------|
+| `stacks` | map[string][PulumiStack](#pulumistack) | A map of names to stacks to get outputs from. The names contains all outputs from the stack |
 
 ### PulumiStack