Add initial docs for dataviews component (#55435)

packages/edit-site/src/components/dataviews/README.md

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+# DataView
+
+This file aims to document the main APIs related to the DataView component.
+
+## View
+
+The view is responsible for configuring how the dataset is visible to the user. For example:
+
+```js
+{
+	type: 'list',
+	page: 1,
+	perPage: 5,
+	sort: {
+		field: 'date',
+		direction: 'desc',
+	},
+	filters: {
+		search: '',
+		author: 2,
+		status: 'publish, draft'
+	},
+	visibleFilters: [ 'search', 'author', 'status' ],
+	hiddenFields: [ 'date', 'featured-image' ],
+	layout: {},
+}
+```
+
+- `type`: one of `list` or `grid`.
+- `page`: the current page.
+- `perPage`: number of records per page.
+- `sort.field`: field used for sorting.
+- `sort.direction`: one of `asc` or `desc`.
+- `filters`: the filters applied to the dataset.
+- `visibleFilters`: the `id` of the filters that are visible in the UI.
+- `hiddenFields`: the `id` of the fields that are hidden in the UI.
+- `layout`: ...
+
+The view configuration is used to retrieve the corresponding entity that holds the dataset:
+
+```js
+const {
+	records: pages,
+	isLoading: isLoadingPages,
+	totalItems,
+	totalPages
+} = useEntityRecords( 'postType', 'page', {
+	per_page: view.perPage,
+	page: view.page,
+	order: view.sort?.direction,
+	orderby: view.sort?.field
+	...view.filters
+} );
+```
+
+## Fields
+
+The fields describe the dataset. For example:
+
+```js
+[
+	{
+		id: 'author',
+		header: __( 'Author' ),
+		getValue: ( { item } ) => item.author,
+		render: ( {item} ) => {
+			return (
+				<a href="...">{ item.author }</a>
+			);
+		},
+		elements: [
+			{ value: 1, label: 'admin' }
+			{ value: 2, label: 'user' }
+		]
+		filters: [
+			{ id: 'author', type: 'enumeration' },
+			{ id: 'author_search', type: 'search' }
+		],
+	},
+]
+```
+
+- `id`: identifier for the field. Unique.
+- `header`: the field name for the UI.
+- `getValue`: function that returns the value of the field.
+- `render`: function that renders the field.
+- `elements`: a set of valid values for the field.
+- `filters`: what filters are available. A filter is an object with `id` and `type` as properties:
+	- `id`: unique identifier for the filter. Matches the entity query param.
+	- `type`: the type of filter. One of `search` or `enumeration`.
+
+
+## DataViews
+
+The UI component responsible for rendering the dataset.
+
+```js
+<DataViews
+	data={ pages }
+	isLoading= { isLoadingPages }
+	fields={ fields }
+	view={ view }
+	onChangeView={ onChangeView }
+	actions={ [ trashPostAction ] }
+	paginationInfo={ { totalItems, totalPages } }
+/>
+```