Include partialRight import from lodash in DimensionControl example (#…

…38088)

The `partialRight` import from lodash was missing from the example, which confused me when I was referencing it (especially having never used that particular utility before).

It would probably be better if the example didn't rely on such an opaque 3rd-party utility, but for now at least it's clear what is being used.

packages/components/src/dimension-control/README.md

@@ -11,6 +11,8 @@ This feature is still experimental. “Experimental” means this is an early im
 In a block's `edit` implementation, render a `<DimensionControl />` component.
 
 ```jsx
+import { partialRight } from 'lodash';
+
 import { registerBlockType } from '@wordpress/blocks';
 import { __ } from '@wordpress/i18n';
 import { DimensionControl } from '@wordpress/components';