Document the user-side plumber rules that make files and directories open in
Kate: the edit-port routing model, setting editor = /usr/bin/kate so files
(with their addr line/col) open in Kate instead of acme, the isdir rule that
opens a directory as a folder (plumb start kate $dir), reloading a running
plumber (9p write plumb/rules), verification, and troubleshooting. Cross-link
from PLAN.md.
Note: ~/lib/plumbing itself lives in the user's home, not the repo; this
documents how to configure it.
Levi Neely