  This note was prepared after the workshop on cdh descent and algebraic
$K$-theory in Hara-mura, Japan (1 - 5 Sept. 2016), to complement the author's
talk on the history and applications of pro cdh descent. In the final section
pro cdh descent is used to define $K$-groups of rigid analytic varieties. This
note was revised and released in light of Kerz, Strunk, and Tamme establishing
pro cdh descent in general (arXiv:1611.08466).
