HPwDuW: Fix links from throughout the site to the resource

[remibetin]

Description

e.g., link to a specific story is now a broken anchor link in the top-level page

• easy ones that are just a link fix and don't need any analysis
• harder ones where we need to make sure that the reference still works 'cause the stories changed a bit

Resources in question:

• [ ] Accessibility Principles: https://github.com/w3c/wai-accessibility-principles/pull/52
• Perspective Videos: https://github.com/w3c/wai-perspective-videos/pull/87
  • [ ] Customizable
  • [ ] Captions
  • [ ] Layout
  • [ ] Understandable
  • [ ] Speech
  • [ ] Controls
  • [ ] Voice
  • [ ] Contrast
  • [ ] Notifications
  • [ ] Keyboard
• [ ] New in WCAG 2.2
• [ ] New in WCAG 2.1
• Easy Checks
  • [ ] Headings
  • [ ] Zoom
• Tips
  • [ ] Developing
  • [ ] Designing
  • [ ] Writing

Resource Shortname

wai-people-use-web