Erratum -- Measurable Graph Combinatorics.

In the paragraph after Theorem 2.5, the paper states "it remains an open problem to compute the precise rate of growth of the measurable chromatic number of the graphs G_n induced by shift actions of free groups of rank n. In fact, this was already known to be (2+o(1))n/\log n". The factor-of-2 improvement on the lower bound follows from a theorem of Rahman and Virág (https://arxiv.org/abs/1402.0485), and the measurable independence ratio of G_n is (1+o(1))\log n/(2n). The details are written up in the following paper of Anton Bernshteyn https://arxiv.org/abs/2105.11557. Thanks to Anton Bernshteyn for pointing out this error.