Update 02-libraries.md: typo
Fixes #1822 Update 02-libraries.md

Assuming #1822 is correct, this should fix it.
Merge pull request #1823 from myqlarson/patch-2

Fixes #1822 Update 02-libraries.md
Merge pull request #1821 from myqlarson/patch-1

Update 02-libraries.md: typo
Fixes #1822 Update 02-libraries.md

If username is unrelated, then I propose `username` rather than `composer` or `acme` to avoid confusion.
Merge pull request #1824 from myqlarson/patch-2

Fixes #1822 Update 02-libraries.md
Update deps