Add BUSL details for Materialize and Zerotier

dosp-survey.ltx

@@ -221,11 +221,19 @@ Change Date: release +3 years
 Change License: Apache License, Version 2.0
 \otsurl{https://about.codecov.io/blog/codecov-is-now-open-source/}
 
-ZeroTier
-% TODO
+ZeroTier (2019-08-23)
+Change Date: the beginning of the fifth calendar year after 2020 license update
+% this may be an oversight by the developers
+Change License: Apache License, Version 2.0
+% https://github.com/zerotier/ZeroTierOne/commit/52a166a71f4e0124c7b22123884911338aa0d698
+
+Materialize (2020-02-07)\footnote{Not to be confused with the Materialize CSS project, which is released under the MIT license.}
+Change Date: +4 years
+Change License: Apache License, Version 2.0
 
-Materialize
-% TODO
+Differently from other BUSL-licensed projects, Materialize uses a bot to update the Change Date
+every day (not just on the occasion of release events), so that it always reflects a date exactly
+four years after the present date.
 
 \subsection{Differences From Other Licensing Strategies}\label{differences}