Docs: new documentation site (#2723)

This commit adds a VitePress build to the main repository,
aiming to ditch GitHub Wiki. Moving further, we're going to
host our own documentation site eithor on GitHub Pages or
something alike.

docs/premium/userspace-wireguard.md

@@ -0,0 +1,25 @@
+---
+sidebarTitle: "Feature: Userspace Wireguard"
+sidebarOrder: 7
+---
+
+# Userspace Wireguard
+
+Due to the dependency on gvisor TCP/IP stack, Wireguard outbound is currently only available in the Premium core.
+
+```yaml
+proxies:
+  - name: "wg"
+    type: wireguard
+    server: 127.0.0.1
+    port: 443
+    ip: 172.16.0.2
+    # ipv6: your_ipv6
+    private-key: eCtXsJZ27+4PbhDkHnB923tkUn2Gj59wZw5wFA75MnU=
+    public-key: Cr8hWlKvtDt7nrvf+f0brNQQzabAqrjfBvas9pmowjo=
+    # preshared-key: base64
+    # remote-dns-resolve: true # remote resolve DNS with `dns` field, default is true
+    # dns: [1.1.1.1, 8.8.8.8]
+    # mtu: 1420
+    udp: true
+```