Update appimage file for valid screenshot and URL

org.kde.plasmashell.metainfo.xml

@@ -70,7 +70,7 @@
   <summary xml:lang="x-test">xxKDE's complete desktop experience. Simple by default, powerful when neededxx</summary>
   <summary xml:lang="zh-CN">KDE 的完整桌面体验。默认简单，需要时强大。</summary>
   <summary xml:lang="zh-TW">KDE 的完整桌面體驗。預設簡潔，需要時足夠強大</summary>
-  <url type="homepage">https://www.kde.org/workspaces/plasmadesktop/</url>
+  <url type="homepage">https://www.kde.org/plasma-desktop</url>
   <url type="bugtracker">https://bugs.kde.org/enter_bug.cgi?format=guided&amp;product=plasmashell</url>
   <project_group>KDE</project_group>
   <provides>
@@ -78,7 +78,7 @@
   </provides>
   <screenshots>
     <screenshot type="default">
-      <caption>Plasma Desktop in Folder View with Clock and Notes Widgets</caption>
+      <caption>Plasma being used as a desktop</caption>
       <caption xml:lang="ar">سطح مكتب بلازما بمنظور المجلّد بودجتيّ السّاعة والملاحظات</caption>
       <caption xml:lang="ca">Escriptori Plasma en vista de carpeta amb els estris rellotge i notes</caption>
       <caption xml:lang="ca-valencia">Escriptori Plasma en vista de carpeta amb els estris rellotge i notes</caption>
@@ -110,7 +110,7 @@
       <caption xml:lang="x-test">xxPlasma Desktop in Folder View with Clock and Notes Widgetsxx</caption>
       <caption xml:lang="zh-CN">有时钟和便笺部件文件夹视图的 Plasma 桌面</caption>
       <caption xml:lang="zh-TW">有著時鐘與便條小工具的 Plasma 桌面資料夾檢視</caption>
-      <image type="source">https://www.kde.org/workspaces/plasmadesktop/screenshots/general-desktop.png</image>
+      <image type="source">https://cdn.kde.org/screenshots/plasma/plasma.png</image>
     </screenshot>
   </screenshots>
 </component>