Help_url added for 5.2 built-in gramplet.gpr.py missing from 5.3 master fork

The module-level constants global help_url values added for the for 5.2 maintenance built-in Gramplets dropped out of the 5.3 master branch built-in gramplets.

GRAMPLET_HELP = _("Gramps_5.2_Wiki_Manual_-_Gramplets#Gramplet_List")
DEBUG_HELP = _("Gramps_5.2_Wiki_Manual_-_Tools#Debug")

register(
    GRAMPLET,
    id="Age on Date",
    name=_("Age on Date"),
    description=_("Gramplet showing ages of living people on a specific date"),
    version="2.0.0",
    gramps_target_version=MODULE_VERSION,
    status=STABLE,
    fname="ageondategramplet.py",
    height=200,
    gramplet="AgeOnDateGramplet",
    gramplet_title=_("Age on Date"),
    help_url=GRAMPLET_HELP,
)