feat: add artplayer-plugin-jassub with initial implementation and documentation

docs/index.html

@@ -120,6 +120,10 @@
                             <a
                                 href="/?libs=./uncompiled/artplayer-plugin-liquid-glass/index.js&example=liquid.glass">artplayer-plugin-liquid-glass</a>
                         </li>
+                        <li>
+                            <a
+                                href="/?libs=./uncompiled/artplayer-plugin-jassub/index.js&example=jassub">artplayer-plugin-jassub</a>
+                        </li>
                     </ul>
                     <ul>
                         <li class="title">Proxys</li>