Add a Caption To an Existing Slide

## Can you think of a better caption?
Each slide can have more than one caption. Check out the current slide show and add a caption (or two).
If you need help, check out the Appendix in the training manual.

Inspect the repository's current slide show to identify an existing slide that can receive a caption, and consult the Appendix in the training manual for the expected format. Add one or two captions and verify that the updated slide show displays them correctly.

Written by the indexing model from the issue text.