Docs: variety of fixes

[jrfnl]

Description

Docs: various textual tweaks

... picked up along the way.

Docs: update a few URLs to https

Follow up to #3762

Docs: fix various incorrect type annotations

Includes a number of fixes previously pulled in (closed) PR #3703.

Suggested changelog entry

N/A

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
  • [ ] This change is only breaking for integrators, not for external standards or end-users.
• [x] Documentation improvement

[jrfnl]

Closing as replaced by https://github.com/PHPCSStandards/PHP_CodeSniffer/pull/94