Notes what 075c7a3 did for ADR-0016 item 8's fallbacks

[johnnyt]

What

ADR-0016's Note of 2026-09-29 ("the Amendment of 2026-09-29 is flipped to accepted") credits item 8's its delay and its event fallbacks to 075c7a3. That commit did not build them: it pinned them with a render test and added one comment to defp timer_edges/2. The fallbacks in the :timer clause of defp edge_line/2 came with the timer edge itself in 40cb469 (2026-09-27) and are already present at a2e008c, the commit the Amendment of 2026-09-29 read its cites at.

This PR appends one dated foot Note to docs/adr/0016-document-describes-itself.md that says so. The flip Note is not edited; the Note carries no Status line and decides nothing. git diff origin/main -- docs/adr/ shows 25 added lines and zero removed. No changelog fragment: changelog.d/README.md excludes docs and ADRs.

Refs: sb-0o4l

Gate

Full mix quality green on the committed tree (3,951 of 3,951 tests, 95.3% coverage, dialyzer clean, ADR cites green: every record citation resolves and is unmoved).

Review (in-turn, direction check of the record text)

Every claim in the Note was checked against the repo at 142a391 (main when this branch was last rebased). git show 075c7a3 -- lib/ changes describe.ex by one added line, a comment above the is_binary(parent) guard in defp timer_edges/2 (describe.ex:534 at 142a391), and no line of defp edge_line/2; 4fdf7f8 has since reworded that comment, and the Note says so rather than restating its old wording. The test a hand-built timer edge with no readable delay or event reads its delay and its event is at describe_test.exs:1010. git log -S'its delay' -- lib/statifier_blocks/describe.ex names 40cb469 (2026-09-27, "Adds the describe's timer edge") as the commit that introduced the fallback string, whose message ties it to ADR-0016's Amendment of 2026-09-27; git show a2e008c:lib/statifier_blocks/describe.ex already carries both fallbacks, and a2e008c is an ancestor of 075c7a3. The fallback lines are at describe.ex:638 and :639 at 142a391, anchored on the :timer clause of defp edge_line/2. The flip Note's own reading of item 8 at 520c6d8 still holds and is left as written. Cites are anchor-qualified and SHA-labelled per docs/adr/README.md; the Note is appended at the end of the file, so no line another record cites moves. Nothing rejected.

Provenance

The branch was rebased onto main after 4fdf7f8 (a comment-only change to describe.ex) landed, and the Note's code cites were re-located by anchor and re-labelled at 142a391 before merge; the full gate re-ran green on the rebased tree.