add routes portal capability (#1769)

Author: calebdoxsey

content/docs/capabilities/img/routes-portal/desktop-client.png

@@ -0,0 +1,49 @@
+---
+title: Pomerium Routes Portal
+lang: en-US
+sidebar_label: 'Routes Portal'
+description: How to quickly view the routes you have access to in Pomerium.
+keywords: [pomerium, routing, portal]
+---
+
+The Pomerium Routes Portal allows a user to see all the routes they have access to. It is available on any domain frontend by Pomerium at the special `/.pomerium/routes` endpoint.
+
+![Routes Portal](./img/routes-portal/routes-portal.png)
+
+This data is also available as JSON at `/.pomerium/api/v1/routes`.
+
+```json
+{
+  "routes": [
+    {
+      "id": "c7cc6f3995e8c6e4",
+      "name": "postgres",
+      "type": "tcp",
+      "from": "tcp+https://postgres.curious-cat-9999.pomerium.app:5432",
+      "description": "",
+      "connect_command": "pomerium-cli tcp postgres.curious-cat-9999.pomerium.app:5432"
+    },
+    {
+      "id": "2116ef165e888f1a",
+      "name": "verify",
+      "type": "http",
+      "from": "https://verify.curious-cat-9999.pomerium.app",
+      "description": ""
+    }
+  ]
+}
+```
+
+### CLI
+
+The Pomerium CLI can list routes via the `routes list` subcommand:
+
+```bash
+pomerium-cli routes list https://curious-cat-9999.pomerium.app
+```
+
+### Desktop Client
+
+The Pomerium Desktop Client can automatically create connections using the Routes Portal.
+
+![Desktop Client](./img/routes-portal/desktop-client.png)

content/docs/capabilities/img/routes-portal/routes-portal.png

@@ -43,6 +43,7 @@ const sidebars = {
         'docs/capabilities/authorization',
         'docs/capabilities/getting-users-identity',
         'docs/capabilities/routing',
+        'docs/capabilities/routes-portal',
         'docs/capabilities/custom-domains',
         // secondary capabilities
         {