Fix typo in book: flag is --owner, not --owners

Author: justinsb

docs/book/basics/project_creation_and_structure.md

@@ -68,7 +68,7 @@ that will be required to build your project.
 
 {% sample lang="bash" %}
 ```bash
-$ kubebuilder init --domain k8s.io --license apache2 --owners "The Kubernetes Authors"
+$ kubebuilder init --domain k8s.io --license apache2 --owner "The Kubernetes Authors"
 ```
 {% endmethod %}