Improve unresolved merge conflicts warning (issue2681)

Suggested by Antoine Pitrou <[e-mail]>

mercurial/localrepo.py

@@ -976,7 +976,7 b' class localrepository(repo.repository):'
             for f in changes[0]:
                 if f in ms and ms[f] == 'u':
                     raise util.Abort(_("unresolved merge conflicts "
-                                                    "(see hg resolve)"))
+                                       "(see hg help resolve)"))
 
             cctx = context.workingctx(self, text, user, date, extra, changes)
             if editor:

tests/test-commit-unresolved.t

@@ -38,7 +38,7 b' Correct the conflict without marking the'
 
   $ echo "ABCD" > A
   $ hg commit -m "Merged"
-  abort: unresolved merge conflicts (see hg resolve)
+  abort: unresolved merge conflicts (see hg help resolve)
   [255]
 
 Mark the conflict as resolved and commit

tests/test-rebase-conflicts.t

@@ -65,7 +65,7 b' Conflicting rebase:'
 Try to continue without solving the conflict:
 
   $ hg rebase --continue 
-  abort: unresolved merge conflicts (see hg resolve)
+  abort: unresolved merge conflicts (see hg help resolve)
   [255]
 
 Conclude rebase: