Add new "wami" app to the list of demos

[captainbrosset]

Thanks for the awesome library!

This issue is a request to add a new app to the demo section of the README file. The app is called wami, and I created it recently.

It can be accessed here: https://microsoftedge.github.io/Demos/wami/
And the source code is available here: https://github.com/MicrosoftEdge/Demos/tree/main/wami

To use the app:

• Either select a flow from the left sidebar or create a new one.
• With a flow select you can then drop images in the drop area on the right, and then click "Run flow" to modify the images according to the steps defined in the flow.
• The steps in a flow are imagemagick commands.

Here is a short screencast of the app:

One more thing, the app is also a Progressive Web App (PWA), so it can be installed on desktop operating systems if you use a Chromium-based browser like Edge or Chrome.