Added help_text for format string
Added help_text for format string

BrendanBerkley/django-report-builder,altanawealth/django-report-builder,altanawealth/django-report-builder,BrendanBerkley/django-report-builder,AbhiAgarwal/django-report-builder,BrendanBerkley/django-report-builder,altanawealth/django-report-builder,AbhiAgarwal/django-report-builder,AbhiAgarwal/django-report-builder