Add index.jelly with a plugin description.

This plugin description will be shown in Jenkins´ plugin manager.

Author: uhafner

src/main/resources/index.jelly

@@ -0,0 +1,8 @@
+<?jelly escape-by-default='true'?>
+
+<div>
+  Provides <a href="https://getbootstrap.com/">Bootstrap 5</a> for Jenkins Plugins.
+  Bootstrap is (according to their self-perception)
+  the world’s most popular front-end component library to build responsive,
+  mobile-first projects on the web.
+</div>