update slack url and twitter (#355)

* update slack url and twitter

use a dedicated url for slack, allowing update in a single place

rename Twitter references to X

* rollback Install NetBird title in navigation menu

next.config.mjs

@@ -24,6 +24,11 @@ const nextConfig = {
     },
     redirects: async () => {
         return [
+            {
+                source: '/slack-url',
+                destination: 'https://join.slack.com/t/netbirdio/shared_invite/zt-36ckpgzva-_V4OFhWhDA8e2v_Fy6zR3w',
+                permanent: false,
+            },
             {
                 source: '/how-to/networks-concept',
                 destination: '/how-to/networks',