Archive in package code used to create dummy data

[bms63]

@bms63 - in admiral core we include the below in the data.R file, is it necessary to request the same for admiralvaccine?
#' @Keywords datasets
#' @family datasets
#' @source

Originally posted by @yangc71 in #33 (comment)

[bms63]

@pharmaverse/admiralvaccines We should figure out a way to store all the code that was used to create the dummy data for admiralvaccines. We can a folder called dummy_data to store it and use .Rbuildignore to prevent it from loading into the package

[bms63]

Probably should also create a readme with how to update/create dummy data