iobroker plugin: "Older entries" footer-link rotates into CHANGELOG_OLD.md instead of staying in README

[krobipd]

Bug

When the iobroker plugin rotates older versions from README.md ## Changelog into CHANGELOG_OLD.md, the footer line Older entries are in [CHANGELOG_OLD.md](CHANGELOG_OLD.md). gets carried along with the rotated entry. After one release the footer ends up in CHANGELOG_OLD.md between old version entries; the README has no footer at all.

Reproduction

1. Set up an adapter with ## Changelog containing >7 entries, last line is the footer link.
2. Run npm run release patch.
3. The plugin rotates the oldest entry into CHANGELOG_OLD.md. Inspect both files.

Expected: footer line stays at the bottom of README ## Changelog.
Actual: footer line moves with the rotated entry into CHANGELOG_OLD.md, README has none.

Reproduced in

• iobroker.govee-smart v2.0.2
• iobroker.parcelapp v0.2.15
• iobroker.beszel v0.3.5
• iobroker.hassemu v1.2.0

Workaround

A `before_commit` hook script removes the stray footer from `CHANGELOG_OLD.md` and restores it at the bottom of README `## Changelog`. A reasonable patch in the plugin would be to detect the `Older entries are in [CHANGELOG_OLD.md]...` pattern as a non-rotatable footer and leave it in place when rotating.

[AlCalzone]

It looks like you changed the automatically generated line the script creates from

Older entries are in CHANGELOG_OLD.md.

to

Older entries have been moved to CHANGELOG_OLD.md.

which breaks the logic that looks for the first line. I'll widen that logic, so it matches variations of the intended line.