added namespace provising example guide (#3109)

Author: droot

scripts/generate_site_sidebar/sidebar_template.md.tmpl

@@ -56,7 +56,7 @@
   - [Contrib](https://catalog.kpt.dev/contrib/ ":target=_self")
 - [Guides](guides/)
   - [The Rationale behind kpt](guides/rationale.md)
-  - [Tenant Onboarding](guides/tenant-onboarding.md)
+  - [Namespace provisioning example)(guides/namespace-provisioning-example.md)
   - [Porch Installation Guide](guides/porch-installation.md)
   - [Porch User Guide](guides/porch-user-guide.md)
 - [FAQ](faq/)