feat: made index main export option only

and added plugin type which i will add to it later on

src/types/index.ts

@@ -35,3 +35,8 @@ export interface PlayerEvents {
   onEnd?: () => void;
   onError?: () => void;
 }
+
+export interface Plugin {
+  name: string;
+  init(player: any): void;
+}