Checks the format of a DOI.
The format must obey https://www.doi.org/doi_handbook/2_Numbering.html#2.2
The DOI should the minimal version.
Hence no doi:, https://doi.org or other prefixes.
An example of a minimal version is 10.21436/inbor.70809860.
The part before the forward slash consists of two or three sets of digits
separated by a dot.
E.g. 10.21436 or 10.21436.1.
The part after the forward slash consists either of only digits or of
two sets of any character separated by a dot.
validate_doi(doi)a string containing the DOI.
Other utils:
add_author(),
add_report_numbers(),
check_dependencies(),
column_start(),
column_width(),
cover_info(),
create_report(),
dyn_table(),
references(),
render_natbib()