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

[yuja (Yuya Nishihara)]

yuja added a comment.


  > We don't have a UI to display obsmarker in core, so for now extensions has to do this.
  
  I know. It would be nice if reviewers can know how the planned UI will be
  to determine whether only --note option should be in the next release or not.

REPOSITORY
  rHG Mercurial

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

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