I've needed to add a similar annotation a number of times. I use sketch lines and notes to build my own. I'm not aware of any out-of-the-box solutions.
if you click on the dimension, then in the "dimension text" on the middle bottom there is a button with a cl and + sign. click on that and click on modifying symbols
if you click on the dimension, then in the "dimension text" on the middle bottom there is a button with a cl and + sign. click on that and click on modifying symbols