A new Site-to-Site setup guide (#480)

* wip: new Site-to-Site guide

* wip: Site-to-Site guide with access controlls

* wip: Site-to-Site without masquerading

* feat: Site-to-Site setup guide

* amended wording/grammar, moved to new 'use cases' directory

* fix: missing some bold terms

* fix: revert headings changes

* Added styling for h4 headers, removed site-to-site doc from how-to directory

* moved images to correct directory

---------

Co-authored-by: Ashley Mensah <ashley@netbird.io>

src/components/NavigationDocs.jsx

@@ -272,6 +272,7 @@ export const docsNavigation = [
     {
      title: 'USE CASES',
      links: [
+         { title: 'Site-to-Site and Site-to-VPN', href: '/use-cases/setup-site-to-site-access' },
          { title: 'Serverless and NetBird', href: '/use-cases/netbird-on-faas' },
          { title: 'Routing peers and Kubernetes', href: '/use-cases/routing-peers-and-kubernetes'},
          { title: 'NetBird Client on AWS ECS', href: '/use-cases/examples'},