covid19swiss 0.1.0

Added a NEWS.md file to track changes to the package.
Created the following vignettes:
- Introduction to the covid19swiss Dataset
- Updating the covid19swiss Dataset
- Geospatial Visualization of Switzerland Cantons (non CRAN vignette)
Created a package site
Added the update_swiss_data function to keep the installed version updated with the Dev version
Added the refresh_covid19swiss and get_info_covid19swiss functions to incorporate the data in the covid19R package

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