D877: releasenotes: display release notes when no filename is specified

[pulkit (Pulkit Goyal)]

pulkit accepted this revision.
pulkit added a comment.


  Can you also update the doc as a follow-up as it says `parse release notes from commit messages into an output file` which is not always the case now.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D877

To: rishabhmadan96, #hg-reviewers, pulkit
Cc: pulkit, mercurial-devel