"Light Mode" in documentation

[ravshansbox]

Scope

Improves an existing behavior

Compatibility

• This is a breaking change

Feature description

Add "Light Mode" to the documentation page

[kettanaito]

Hi, @ravshansbox. Thanks for raising this. The effort behind the light mode is tracked here mswjs/mswjs.io#357. It will likely need a huge update after I merge the new site structure.