docs: change wrong icon for night/day

[nmerget]

Proposed changes

fixes icon in: https://db-ui.github.io/mono/review/main/foundations/colors/color-schemes

Types of changes

• [ ] Bugfix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Refactoring (fix on existing components or architectural decisions)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [x] Documentation Update (if none of the other choices apply)

Further comments

[github-actions[bot]]

🔭🐙🐈 Test this branch here: https://db-ui.github.io/mono/review/docs-change-wrong-icon