*Description of changes: Adding a JPG version of sample green screen image and adding some brief instructions on using it, due to the fact this workshop is now often being run remotely.
I ideally the front end could also be updated to allow PNG files, which I would be happy to make the changes for but the front end assets are not part of this repository.
By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.
*Issue #, if available:#44
*Description of changes: Adding a JPG version of sample green screen image and adding some brief instructions on using it, due to the fact this workshop is now often being run remotely.
I ideally the front end could also be updated to allow PNG files, which I would be happy to make the changes for but the front end assets are not part of this repository.
By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.