Merge pull request #1982 from system-ui/lachlanjc-docs-form-colors

docs(components): Include form control color names

packages/docs/src/pages/components/forms.mdx

@@ -67,6 +67,16 @@ The entire form should be wrapped in a `<form>` element.
 
 ## Theming
 
+Many of the included form components (e.g. Checkbox, Radio, Slider) use 3 colors for their default appearance:
+
+- `gray`, for the default state
+- `primary`, for the active state
+- `highlight`, for the focus outline
+
+If you’re only looking to change the colors, providing custom values for these colors in `theme.colors` is the easiest path.
+
+### Further customization
+
 Add styles for form elements in the `theme.forms` object.
 
 ```js