errata: rejection sampling a unit disk

[leggcg]

Caption of figure 13.6: Rejection Sampling a Circle. One approach to finding uniform points in the unit circle is to sample uniform random points in the unit square and reject all that lie outside the circle (red points). The remaining points will be uniformly distributed within the circle.
The circumscribed square is 2x2.

The title of the example where that figure is located is: Example: Rejection Sampling a Unit Circle
Changing to unit disk would make it clearer, or even to points inside a unit circle to go with the idea of the inside/outside test.