Duke colors

Noting them here to remove `Color_Guide.R`

- Duke Royal Blue: `#00539B`
- Duke Navy Blue: `#012169`
- Copper: `#C84E00`
- Persimmon: `#E89923`
- Cast Iron: `#262626`
- Whisper Gray: `#F3F2F1`
- Granite: `#B5B5B5`
- Dandelion: `#FFD960`
- Piedmont: `#A1B70D`
- Ironweed: `#993399`
- Eno: `#339898`
