feat: Add userscript header's license

Author: pboymt

plugins/userscript.plugin.ts

@@ -23,6 +23,7 @@ interface UserScriptOptions {
     updateURL: string;
     downloadURL: string;
     supportURL: string;
+    license: string;
     include: string[];
     match: string[];
     exclude: string[];
@@ -131,6 +132,10 @@ export function generateHeader() {
     if (userscript.supportURL) {
         headers.push(`// @supportURL ${userscript.supportURL}`);
     }
+    // Add userscript header's license.
+    if (userscript.license) {
+        headers.push(`// @license ${userscript.license}`);
+    }
     // Add userscript header's includes.
     if (userscript.include && userscript.include instanceof Array) {
         for (const include of userscript.include) {