Q. Where do I list availability on my resume?
A. Simple answer; you don’t. In the rare case that you need to speak to availability at all, you would do so in the cover letter.
If you are applying for a position that requires specific availability, then it can be assumed that you meet those requirements (so you don’t need to state that you do). If your availability differs from the job requirements, then you can share that in the cover letter and speak to why you are still a strong fit for the position.
There are always outliers, but in all of my years on both sides of the table, I have yet to come across a situation where availability actually belongs on the resume.