docs: update docs of labels in resourcemanager_project resource (#951)

- add hint that networkArea can only be attached on project creation

Author: marceljk

docs/resources/resourcemanager_project.md

@@ -46,7 +46,8 @@ import {
 
 ### 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 ^$|[A-ZÄÜÖa-zäüöß0-9_-]{1,64}. To add a project to a STACKIT Network Area, setting the label `networkArea=<networkAreaID>` is required.
+- `labels` (Map of String) Labels are key-value string pairs which can be attached to a resource container. A label key must match the regex [A-ZÄÜÖa-zäüöß0-9_-]{1,64}. A label value must match the regex ^$|[A-ZÄÜÖa-zäüöß0-9_-]{1,64}.  
+To create a project within a STACKIT Network Area, setting the label `networkArea=<networkAreaID>` is required. This can not be changed after project creation.
 
 ### Read-Only
 

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

@@ -100,7 +100,7 @@ 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 ^$|[A-ZÄÜÖa-zäüöß0-9_-]{1,64}. To add a project to a STACKIT Network Area, setting the label `networkArea=<networkAreaID>` is required.",
+		"labels":              "Labels are key-value string pairs which can be attached to a resource container. A label key must match the regex [A-ZÄÜÖa-zäüöß0-9_-]{1,64}. A label value must match the regex ^$|[A-ZÄÜÖa-zäüöß0-9_-]{1,64}.  \nTo create a project within a STACKIT Network Area, setting the label `networkArea=<networkAreaID>` is required. This can not be changed after project creation.",
 		"owner_email":         "Email address of the owner of the project. This value is only considered during creation. Changing it afterwards will have no effect.",
 	}