Extend update instructions
Add prelude-find-user-init-file
Add prelude-find-shell-init-file
Add anzu
Disable anzu temporarily due to a bug in it
Add prelude-show-foreign-packages
Revert "Disable anzu temporarily due to a bug in it"

This reverts commit 239571f17be8cff4381d583b8ea4388024f11703.
Merge remote-tracking branch 'upstream/master'