Docs(shortcuts): add expr and starlark (#2759)

Signed-off-by: Birkhoff Lee <git@birkhoff.me>

docs/.vitepress/config.ts

@@ -71,6 +71,13 @@ export default defineConfig({
 
   base: '/clash/',
 
+  head: [
+    [
+      'link',
+      { rel: 'icon', type: "image/x-icon", href: '/clash/logo.png' }
+    ],
+  ],
+
   themeConfig: {
     outline: 'deep',
 

docs/premium/script-shortcuts.md

@@ -7,12 +7,10 @@ sidebarOrder: 6
 
 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 latter feature, for the former, see [Script](./script.md).
+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 latter feature. For the former, see [Script](./script.md).
 
 This feature enables the use of script in `rules` mode. By default, DNS resolution takes place for SCRIPT rules. `no-resolve` can be appended to the rule to prevent the resolution. (i.e.: `SCRIPT,quic,DIRECT,no-resolve`)
 
-**NOTE: ****`src_port`**** and ****`dst_port`**** are number**
-
 ```yaml
 mode: Rule
 
@@ -27,11 +25,33 @@ rules:
   - SCRIPT,quic,REJECT
 ```
 
-## Function Definitions
+## Evaluation Engines
+
+[Expr](https://expr.medv.io/) is used as the default engine for Script Shortcuts, offering 10x to 20x performance boost compared to Starlark.
+
+[Starlark](https://github.com/google/starlark-go) is a Python-like langauge for configuration purposes, you can also use it for Script Shortcuts.
+
+## Variables
+
+- network: string
+- type: string
+- src_ip: string
+- dst_ip: string
+- src_port: uint16
+- dst_port: uint16
+- host: string
+- process_path: string
+
+::: warning
+Starlark is missing `process_path` variable for now.
+:::
+
+## Functions
 
 ```ts
 type resolve_ip = (host: string) => string // ip string
 type in_cidr = (ip: string, cidr: string) => boolean // ip in cidr
+type in_ipset = (name: string, ip: string) => boolean // ip in ipset
 type geoip = (ip: string) => string // country code
 type match_provider = (name: string) => boolean // in rule provider
 type resolve_process_name = () => string // find process name (curl .e.g)