TODO.md: keep only open work (closes #167)

Remove the Completed Steps section and the Status sentence saying the
file records history. Git keeps the history. The Workflow step that
recorded finished work in Completed Steps now deletes Next Step instead.

Model: opus-5-5

README.md

@@ -114,20 +114,15 @@ docker run --rm -v /srv:/srv:ro -v /var/lib/sfdupes:/var/lib/sfdupes \
 Run `scan` as root, so that it can read every file. `scan` warns about a
 directory it cannot read, and about a new or changed file it cannot read. It
 skips the path and deletes the records at or below it (see "Rules for the
-walk").
-
-An unmounted disk leaves its mount point empty, so `scan` deletes every record
-under it, and the next scan reads every file on the disk again. Test the mount
-point of each disk at or below `/srv` with its own `mountpoint -q`, joined with
-`&&`, and test `/srv` only when it is one. As the file `/etc/cron.d/sfdupes`:
+walk"). As the file `/etc/cron.d/sfdupes`:
 
 ```
-30 3 * * * root if mountpoint -q /srv; then /usr/local/bin/sfdupes scan /srv 2>>/var/log/sfdupes.log || tail -n 3 /var/log/sfdupes.log; else echo "a disk is not mounted; scan of /srv skipped"; fi
+30 3 * * * root /usr/local/bin/sfdupes scan /srv 2>>/var/log/sfdupes.log || tail -n 3 /var/log/sfdupes.log
 ```
 
 - The first scan creates `/var/lib/sfdupes/db.sqlite` and its directory. To keep
-  the database elsewhere, put `SFDUPES_DATABASE=/path/to/db.sqlite` directly
-  before `/usr/local/bin/sfdupes`.
+  the database elsewhere, put `SFDUPES_DATABASE=/path/to/db.sqlite` before the
+  command on the same line.
 - `scan` writes nothing to stdout. Its stderr, appended here to
   `/var/log/sfdupes.log`, holds:
     - one line naming the database;