minor, pass unabridged data to add_tag() in rotz-add

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
Merge branch 'cmd/add'

* cmd/add:
  minor, pass unabridged data to add_tag() in rotz-add
  doc, provide a simple README.md
  minor, allow to specify database file via --database in rotz-show
  minor, allow to specify database file via --database in rotz-del
  minor, allow to specify database file via --database in rotz-add