message: document scale-down-to-width
diff: import { modifier } from 'ember-modifier';
  /**
  - * Scale an element's child down to fit a given width
  + * This modifier is kind of awkward. Layouts behave as if the scaled element
  + * is still the same width as before, so we need to add a negative margin for height.
  + * It allows insertion of arbitrary content for previews - we need this for workflows
  + * to follow the layout size while displaying previews using the same components (except scaled down);
  + * and for the image editor to do the same, if necessary. I'm imagining the image editor to
  + * allow clicking on a scaled-down component and seeing a blown up version; though that is more
  + * of a possible future improvement.
  + *
  + * Possible improvements to this modifier:
  + * - make a component that uses scale-down-to-width internally/ applies similar logic and wraps a containing div around.
  + * - to avoid the margin bottom from not being overwritable.
  + * - to have the scale in state, as a number that can be displayed optionally / provided
  + * - window resize handling
  + */
  +
  +/**
  + * Sets an element's width to a given width,
  + * and scale its child down to fit that width.
  + * Only supports one HTML Element child at the moment.
  *
  * @param element The container element
  * @param params Array of length 1 that contains a single string for the width of the element
  @@ -16,7 +34,9 @@ function scaleDownToWidth(element: HTMLElement, params: string[]) {
  }
  if (children.length > 1) {
  - throw new Error('scale-to-fit cannot support multiple children');
  + throw new Error(
  + 'scale-down-to-width cannot support more than one child node'
  + );
  }
  let child = children[0] as HTMLElement;
  