[Stable10] Add common footer to notifications

[VicDeo]

Backport of #206
Closes #205

[codecov-io]

Codecov Report

Merging #207 into stable10 will not change coverage.
The diff coverage is n/a.

@@             Coverage Diff             @@
##             stable10     #207   +/-   ##
===========================================
  Coverage       89.55%   89.55%           
  Complexity        133      133           
===========================================
  Files              18       18           
  Lines             536      536           
===========================================
  Hits              480      480           
  Misses             56       56

Flag	Coverage Δ	Complexity Δ
#phpunit	89.55% <ø> (ø)	133 <ø> (ø)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 8cee36d...365a73b. Read the comment docs.

[PVince81]

merging this despite code freeze: reasons:

• simple change with minimal additional QA overhead
• to not bother theme admins again in a future release to go back adjusting theme templates again