docs: add hint on how to create a project within sna (#722)

Author: h3adex

docs/resources/resourcemanager_project.md

@@ -18,6 +18,7 @@ resource "stackit_resourcemanager_project" "example" {
   name                = "example-container"
   labels = {
     "Label 1" = "foo"
+    // "networkArea" = stackit_network_area.foo.network_area_id
   }
   owner_email = "john.doe@stackit.cloud"
 }
@@ -34,10 +35,10 @@ resource "stackit_resourcemanager_project" "example" {
 
 ### Optional
 
-- `labels` (Map of String) Labels are key-value string pairs which can be attached to a resource container. A label key must match the regex [A-ZÄÜÖa-zäüöß0-9_-]{1,64}. A label value must match the regex ^$|[A-ZÄÜÖa-zäüöß0-9_-]{1,64}
+- `labels` (Map of String) Labels are key-value string pairs which can be attached to a resource container. A label key must match the regex [A-ZÄÜÖa-zäüöß0-9_-]{1,64}. A label value must match the regex ^$|[A-ZÄÜÖa-zäüöß0-9_-]{1,64}. To add a project to a STACKIT Network Area, setting the label `networkArea=<networkAreaID>` is required.
 
 ### Read-Only
 
 - `container_id` (String) Project container ID. Globally unique, user-friendly identifier.
 - `id` (String) Terraform's internal resource ID. It is structured as "`container_id`".
-- `project_id` (String) Project UUID identifier. This is the ID that can be used in most of the other resources to identify the project.
+- `project_id` (String) Project UUID identifier. This is the ID that can be used in most of the other resources to identify the project.

examples/resources/stackit_resourcemanager_project/resource.tf

@@ -3,6 +3,7 @@ resource "stackit_resourcemanager_project" "example" {
   name                = "example-container"
   labels = {
     "Label 1" = "foo"
+    // "networkArea" = stackit_network_area.foo.network_area_id
   }
   owner_email = "john.doe@stackit.cloud"
 }

stackit/internal/services/resourcemanager/project/resource.go

@@ -152,7 +152,7 @@ func (r *projectResource) Schema(_ context.Context, _ resource.SchemaRequest, re
 		"container_id":                "Project container ID. Globally unique, user-friendly identifier.",
 		"parent_container_id":         "Parent resource identifier. Both container ID (user-friendly) and UUID are supported",
 		"name":                        "Project name.",
-		"labels":                      "Labels are key-value string pairs which can be attached to a resource container. A label key must match the regex [A-ZÄÜÖa-zäüöß0-9_-]{1,64}. A label value must match the regex ^$|[A-ZÄÜÖa-zäüöß0-9_-]{1,64}",
+		"labels":                      "Labels are key-value string pairs which can be attached to a resource container. A label key must match the regex [A-ZÄÜÖa-zäüöß0-9_-]{1,64}. A label value must match the regex ^$|[A-ZÄÜÖa-zäüöß0-9_-]{1,64}. To add a project to a STACKIT Network Area, setting the label `networkArea=<networkAreaID>` is required.",
 		"owner_email":                 "Email address of the owner of the project. This value is only considered during creation. Changing it afterwards will have no effect.",
 		"members":                     "The members assigned to the project. At least one subject needs to be a user, and not a client or service account. This value is only considered during creation. Changing it afterwards will have no effect.",
 		"members.role":                fmt.Sprintf("The role of the member in the project. Possible values include, but are not limited to: `owner`, `editor`, `reader`. Legacy roles (%s) are not supported.", strings.Join(utils.QuoteValues(utils.LegacyProjectRoles), ", ")),