Add missing "should" to roxygen docs

[mthomas-ketchbrook]

Thanks so much for this package! It's a huge lifesaver for a lot of my team's work.

I found what I think was a missing (and important) "should" keyword in the documentation for the req_auth_basic() function. When adding this word to the roxygen param, I kept the line width to 80 characters.

Let me know if you'd like me to add another commit that also updates the associated .Rd file, or if that is part of the automated build process.

[hadley]

/document

[hadley]

@mthomas-ketchbrook in general, it's slightly more convenient if you include the generated .Rd file, but it's also very easy for me to add after the fact.

Thanks for fixing this!

[mthomas-ketchbrook]

@hadley I will make sure to do that going forward -- thank you!