use DEFAULT theme key

[huphtur]

TW 2.0 now uses a DEFAULT theme key. Be great to have that inserted into the color string.

For example: #bb5a27 would produce:

darkorange: {
  50: '#faf6ee',
  100: '#fbefd7',
  200: '#f8e0aa',
  300: '#f5c76a',
  400: '#f2a12e',
  500: '#f07a14',
  600: '#e3550d',
  DEFAULT: '#bb5a27',
  700: '#c13f11',
  800: '#9a3217',
  900: '#7c2917',
},

[huphtur]

(And yes, that's really a brand color I'm working with for a client 🤦‍♂️)

[marcorieser]

I'm not sure if DEFAULT should be the same color as shade 500 or its own color.