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 current slide show to find an existing slide that can accept another caption, and consult the Appendix in the training manual for the expected format. Add one or two captions to that slide and verify that the slide show still presents them correctly.

索引モデルが issue の本文から書いたものです。