Add possibility to overwrite existing .R roxygen documentation file using setup_roxygen()

[larnsce]

Problem statement:

• I exported a dataframe as ghedata, then wrote the dictionary, then used setup_roxygen()
• I then realized I wanted the data resource to be titled people
• I needed to delete all resources related to ghedata before I could use ``setup_roxygen()` again

This might be better placed in documentation rather than adapting a function.