Fix missing x in inde.umd.js

Closes #3396157

README.md

@@ -40,7 +40,7 @@ for further information.
 This module uses a CDN for appraisal purposes but you should install the
 slide-element javascript library in your site if you decide to use it. Save
 https://unpkg.com/slide-element@2.3.1/dist/index.umd.js in your web root as
-`/libraries/slide-element/inde.umd.js`.
+`/libraries/slide-element/index.umd.js`.
 
 
 ## Configuration