docs: rename Network Routes to Routes, deprecate, and relocate Browser Client Architecture (#792)

* docs: rename Network Routes to Routes, deprecate, and relocate Browser Client Architecture

- Rename the docs sidebar entry "Network Routes" to "Routes" and the page H1
- Add a deprecation note to the Routes page: all use cases except exit nodes
  have moved to Networks; reconcile the body framing accordingly
- Move Browser Client Architecture under Peers > Browser Client
  (/manage/peers/browser-client/architecture), nest the nav, add a redirect,
  and update cross-links
- Shrink the site-to-site Architecture diagram boxes to fit their content

* docs: rename Routes nav 'Concept' link to 'Overview'

src/components/NavigationDocs.jsx

@@ -37,10 +37,6 @@ export const docsNavigation = [
         title: 'Ports & Firewalls',
         href: '/about-netbird/ports-and-firewalls',
       },
-      {
-        title: 'Browser Client Architecture',
-        href: '/about-netbird/browser-client-architecture',
-      },
       { title: 'FAQ', href: '/about-netbird/faq' },
       /*{ title: 'Whats new in version xx', href: '/welcome/how-netbird-works' },
             { title: 'Release notes', href: '/about-netbird/netbird-vs-traditional-vpn' },*/
@@ -101,7 +97,17 @@ export const docsNavigation = [
             title: 'Bootstrap via Config File',
             href: '/manage/peers/bootstrap-via-config-file',
           },
-          { title: 'Browser Client', href: '/manage/peers/browser-client' },
+          {
+            title: 'Browser Client',
+            isOpen: false,
+            links: [
+              { title: 'Overview', href: '/manage/peers/browser-client' },
+              {
+                title: 'Architecture',
+                href: '/manage/peers/browser-client/architecture',
+              },
+            ],
+          },
           { title: 'SSH', href: '/manage/peers/ssh' },
           { title: 'Lazy Connections', href: '/manage/peers/lazy-connection' },
           { title: 'Remote Jobs', href: '/manage/peers/remote-jobs' },
@@ -221,10 +227,10 @@ export const docsNavigation = [
         ],
       },
       {
-        title: 'Network Routes',
+        title: 'Routes',
         isOpen: false,
         links: [
-          { title: 'Concept', href: '/manage/network-routes' },
+          { title: 'Overview', href: '/manage/network-routes' },
           {
             title: 'Use Cases',
             isOpen: false,