Equity/accessibility issue in Memory and Cognitive Load episode

### How could the content be improved?

We discovered after the "Test your Working Memory" exercise this week than one of our participants was dyslexic and so found this activity very challenging and demotivating.

There is an accessible option, but with the note "If you are unable to use this activity, ask your Trainer to implement the analog version of this test". This goes against Carpentries accessibility and universal design principles in that it puts the requirement on the learner to request extra support (since as a 'hidden disability' the instructors would not be aware of the need to use the analog version), and since it's a relatively quick exercise to introduce, there's not much time for them to raise issues anyway.

Perhaps we could look out for an alternative exercise (perhaps one with spoken words already included?) to use as the default version of this.

### Which part of the content does your suggestion apply to?

https://carpentries.github.io/instructor-training/05-memory.html#test-your-working-memory