add 64_(ansi|iso) Community Layouts in keyboards

[dunk2k]

Description

• add respective 64 Community Layout(s) to board with same layout name and matching key matrix information.
  • where applicable, renamed layout name to Community Layout name, alias added
  • applicable 60_* Community Layouts included, as not to clash (merge conflict) with other 60_ Community Layout PRs
• correct ISO Enter key sequence in layouts, and keymap if applicable, for ISO layouts
• add matrix_diagram.md for multiple layout boards, where accurate information is available
• add (if missing) or change image URL (if link broken) in readme.md, where image available

Keyboard specific:

• DZ60:
  • removed 60_abnt2 layout; this board doesn't support 1u-1.75u RShift

Types of Changes

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

Issues Fixed or Closed by This PR

• n/a

Checklist

• 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).