9-month résumé gap, advice?, marketing coordinator here

My résumé shows a gap from a layoff and some health issues. I have been trying to stay organised about it. I am not sure how much to explain. How did you handle it on your résumé?

I was hired after a 9-month gap. The manager said the skills test mattered more than the dates.

I listed the volunteering and course under the same dates and kept the explanation to a sentence in the cover letter.