R/set_ref_properties.R
add_keyword.Rdadd_another_keyword differs from add_keywords in that it does not replace the existing set of keywords but instead just adds one (or more - haven't tested multiple keywords yet) to the reference.
add_keyword(reference_id, keyword, dev = TRUE)NULL (invisibly)
if (FALSE) { # \dontrun{
add_keyword(1234567, "Ants")} # }