docs: Improve documentation

[sergioregueira]

Description

This pull request updates documentation with common doubts of new users.

• Update old references from zeit/ms to vercel/ms because the company changed its name.
• Point out that jwt.verify() determines the supported algorithms based on secretOrPublicKey when they are not explicitly defined.
• Point out that None algorithm is disallowed on jwt.verify() when secretOrPublicKey is specified unless admitted explicitly.
• Remove trailing spaces.

Testing

No tests because this pull request only updates documentation.

Checklist

• I have added documentation for new/changed functionality in this PR or in auth0.com/docs
• All active GitHub checks for tests, formatting, and security are passing
• The correct base branch is being used, if not master