Document cachix

README.md

@@ -74,6 +74,14 @@ x86_64-unknown-genode-clang++ -v
 
 ## Tips and tricks
 
+### Binary cache
+
+Binaries and other artifacts are available from [Cachix](https://app.cachix.org/).
+
+```sh
+cachix use sigil
+```
+
 ### How to add missing Genode ports to a Genode depot package?
 
 The missing ports as indicated by a depot build failure must be added to