D1095: amend: add a flag `-n/--note` to store note with amend

[durin42 (Augie Fackler)]

durin42 added a comment.


  (Thanks to @yuja for reviewing this new feature so I could have more confidence landing the patch this late in the cycle.)

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D1095

To: pulkit, #hg-reviewers, dlax, yuja, durin42
Cc: yuja, mercurial-devel