Documentation Link

https://matplotlib.org/devdocs/users/prev_whats_new/whats_new_3.4.0.html?highlight=bracket#angles-on-bracket-arrow-styles

Problem

I can't tell from this figure what Angle = 60 is relative to, since the top angle is >60 and the lower angle is <60 in the first example, and '0 degrees means perpendicular to the line' is buried in the api docs (I missed what that means like 6 times)

Suggested improvement

An example, that's cross referenced against the API docs, where the angle is marked up, similar to the scale invariant docs

I think it'd be nice to include the formulas for setting the bracket horizontal or vertical relative to the axes, but that's totally extra. I think it's a good first issue since it's completely standalone, a relatively small addition, and this information is missing.