doc: add release note for error handling when VerifyDB dosn't finish successfully

Summary: This concludes backport of core#25574

Test Plan: proof reading

Reviewers: #bitcoin_abc, Fabien, bytesofman

Reviewed By: #bitcoin_abc, Fabien, bytesofman

Subscribers: bytesofman, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D14930