debugdiscovery: correct and clean up command synopsis
This does a few things:
* Changes "-r" to "--rev", since "-r" is not a valid short form
* Removes non-existent "-l" and "-b" options
* Removes "..." after options, since we don't usually have that
Differential Revision: https://phab.mercurial-scm.org/D1706
@echo off
powershell -NoProfile -ExecutionPolicy unrestricted -Command "& '%~dp0\editmergeps.ps1' %*"