Add package name help file.

[leppott]

Is your feature request related to a problem? Please describe.
What user to get something if type "??BioMonTools".

Describe the solution you'd like
usethis::use_r("package-doc")

Then edit the file in the "R" folder with the package name.

Looks like the baytrends one.
https://github.com/tetratech/baytrends/blob/main/R/baytrends.R

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.