Add new mithril logo and give credit

[ch1bo]

Content

Add new mithril logo and give credit to creator

Pre-submit checklist

• Branch
  • [ ] Tests are provided (if possible)
  • [ ] Crates versions are updated (if relevant)
  • [x] CHANGELOG file is updated (if relevant)
  • [x] Commit sequence broadly makes sense
  • [x] Key commits have useful messages
• PR
  • [ ] No clippy warnings in the CI
  • [ ] Self-reviewed the diff
  • [x] Useful pull request description
  • [x] Reviewer requested
• Documentation
  • [x] Update README file (if relevant)
  • [x] Update documentation website (if relevant)
  • [ ] Add dev blog post (if relevant)

[github-actions[bot]]

Test Results

    3 files  ±0     43 suites  ±0   8m 29s :stopwatch: +15s   976 tests ±0    976 :white_check_mark: ±0  0 :zzz: ±0  0 :x: ±0  1 070 runs  ±0  1 070 :white_check_mark: ±0  0 :zzz: ±0  0 :x: ±0 

Results for commit 235519e1. ± Comparison against base commit cf84a951.

:recycle: This comment has been updated with latest results.

[ch1bo]

Note that this is still missing the adaptive svg colors via a @media query.