Modify readme.txt

Readme.txt

@@ -7,4 +7,7 @@ Important: Inside the unzipped folder, click on the application named "XML Gener
 
 People on other Operating Systems (Mac and Linux) should consider running the application from souce from the github link given above, or try out some of the experimental builds under the releases on github.
 
-The app is written in python and uses the PyQt5 framework.
+The app is written in python and uses the PyQt5 framework.
+
+UPDATE: A web version of this tool is available at https://uncertainprod.github.io/FNF-Spritesheet-XML-generator-Web/
+which you can use in case the desktop app does not work or isn't supported on your device