Add screenshots for recent enhancements

[jeffpaul]

Is your enhancement related to a problem? Please describe.

Recent enhancements have not been well-documented in the readme/screenshots so let's do the following:

• [ ] generate screenshots (see Designs section below for ones needed)
• [ ] add to .wordpress-org director
• [ ] reference in readme.txt & readme.md files

Designs

Generate screenshots for the following:

• https://github.com/10up/simple-podcasting/pull/241
• https://github.com/10up/simple-podcasting/pull/214

• 221

Describe alternatives you've considered

n/a

Code of Conduct

• [X] I agree to follow this project's Code of Conduct