docs: update README with new !artist, !playlist, FM fix, and QQ playlist features

src/bot/instance.ts

@@ -722,9 +722,11 @@ export class BotInstance extends EventEmitter {
       `${p}queue        — Show queue`,
       `${p}mode <seq|loop|random|rloop> — Play mode`,
       `${p}playlist <name or id> — Load playlist by name or ID`,
+      `${p}playlist -q <name or id> — Load playlist from QQ Music`,
       `${p}album <id>   — Load album`,
       `${p}fm           — Personal FM (NetEase)`,
       `${p}artist <name> — Play songs by artist (loop)`,
+      `${p}artist -q <name> — Artist loop from QQ Music`,
       `${p}vote         — Vote to skip`,
       `${p}lyrics       — Show lyrics`,
       `${p}now          — Current song info`,