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/script.md

@@ -0,0 +1,70 @@
+---
+sidebarTitle: "Feature: Script"
+sidebarOrder: 5
+---
+
+# Script
+
+Clash Premium implements the Scripting feature powered by Python3, enableing users to programmatically select policies for the packets with dynamic flexibility.
+
+You can either controll the entire rule-matching engine with a single Python script, or define a number of shortcuts and use them in companion with the regular rules. This page refers to the first feature, for the latter, see [Script Shortcuts](./script-shortcuts.md).
+
+## Scripting the entire rule-matching engine
+
+```yaml
+mode: Script
+
+# https://lancellc.gitbook.io/clash/clash-config-file/script
+script:
+  code: |
+    def main(ctx, metadata):
+      ip = metadata["dst_ip"] = ctx.resolve_ip(metadata["host"])
+      if ip == "":
+        return "DIRECT"
+
+      code = ctx.geoip(ip)
+      if code == "LAN" or code == "CN":
+        return "DIRECT"
+
+      return "Proxy" # default policy for requests which are not matched by any other script
+```
+
+If you want to use ip rules (i.e.: IP-CIDR, GEOIP, etc), you will first need to manually resolve IP addresses and assign them to metadata:
+
+```python
+def main(ctx, metadata):
+    # ctx.rule_providers["geoip"].match(metadata) return false
+
+    ip = ctx.resolve_ip(metadata["host"])
+    if ip == "":
+        return "DIRECT"
+    metadata["dst_ip"] = ip
+
+    # ctx.rule_providers["iprule"].match(metadata) return true
+
+    return "Proxy"
+```
+
+Interface definition for Metadata and Context:
+
+```ts
+interface Metadata {
+  type: string // socks5、http
+  network: string // tcp
+  host: string
+  src_ip: string
+  src_port: string
+  dst_ip: string
+  dst_port: string
+}
+
+interface Context {
+  resolve_ip: (host: string) => string // ip string
+  resolve_process_name: (metadata: Metadata) => string
+  resolve_process_path: (metadata: Metadata) => string
+  geoip: (ip: string) => string // country code
+  log: (log: string) => void
+  proxy_providers: Record<string, Array<{ name: string, alive: boolean, delay: number }>>
+  rule_providers: Record<string, { match: (metadata: Metadata) => boolean }>
+}
+```