Clarify triceps pushdown variations

It would be nicer stated as:

- triceps rope push down

- tricep bar push down

- triceps rope one arm push down

This way, you don’t first have to look at the video, to see if you would like to swap your old exercise with the new one.

Met vriendelijke groet,

Raymond Puijk

[Note to team: change current pushdown to rope and add bar and one-arm variations.]