Update feature_layers.md

[Falthazar]

Fixed broken links

Description

Multiple links where missing the file extension for docs (.md) and fixed the link for the Tap Dance link to go to example 5.

Types of Changes

• Core
• [ x] Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Issues Fixed or Closed by This PR

Checklist

• [x ] My code follows the code style of this project: C, Python
• I have read the PR Checklist document and have made the appropriate changes.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[daskygit]

#24151