calc_biomass documentation

[kdorheim]

There is minimal documentation for the data frame returned with calc_biomass and is not included in fd_metadata.

In the @return section can add some notes with the form, with an item for each column, this documentation will show up with the help(fortedata) and will to the pkgdown documentation.

#' \describe{
#'   \item{One}{First item}
#'   \item{Two}{Second item}
#' }

[atkinsjeff]

Hmmm got it. Working on it now. I was probably thinking of this in a backwards way intiailly.