Note to prefer $() over ``, and update single example to conform

[matthewcurry]

Hello,

Most code style guides dictate that $() be used instead of `` for command substitution. I made a very small change to your document to encourage its use.

Thanks,
Matthew

[samumbach]

Nice catch, @matthewcurry 😃

I support this 💯 . We might want to swap the order of `` and $() in the prose and sample code block, too, just to reinforce that $() is more common (or should be... 😉 )

[matthewcurry]

Hey, I added a commit to make the change you suggested.