Prep cran `v0.2.0`

[AARON-CLARK]

Need to cut a new release to address failing R CMD CHECK on CRAN (#155).

In general, this PR just follows the steps outlined here RE: cutting new releases for master and/or CRAN.

In summary, this PR:

• updates authorship (congrats @Jeff & @tdwils!)
• improves readability of the README
• Adds a vignette builder
• cleans the news file
• Adds @return values to some exported functions
• Adds @noRd tags to others
• Decreases the size of internal data example_dat1 and example_dat2 in order to shrink the installed pkg size <= 5MB
• General formatting
• Updates cran-comments.md
• fixes spelling errors and updates wordlist
• updated riskmetric badge since some metrics aren't supported yet
• update pkgdown workflow to run for PRs against devel