message: Fix theming docs
diff: @@ -20,9 +20,11 @@ import { ThemeProvider, css } from 'bumbag';
  import { lighten } from 'polished';
  const theme = {
  - global: css`
  + global: {
  + base: css`
  font-family: 'Comic Sans MS'
  - `,
  + `
  + },
  palette: {
  primary: lighten(0.2, 'blue')
  },
  @@ -57,7 +59,7 @@ If you decide to not use the default Bumbag theme and roll out your own, just ad
  import { ThemeProvider, defaultTheme } from 'bumbag';
  const App = () => (
  - <ThemeProvider isStandalone theme={defaultTheme}>
  + <ThemeProvider isStandalone theme={defaultTheme()}>
  // ... your app
  </ThemeProvider>
  );
  