issue-1363: Allow null in "selectedKey" to avoid typing problems, doc… (#2676)

* issue-1363: Allow null in "selectedKey" to avoid typing problems, document using "null" to clear key selection

* remove workaround example

* remove workaround story

* Update packages/@react-spectrum/picker/docs/Picker.mdx

Co-authored-by: Robert Snow <[email protected]>
Co-authored-by: Danni <[email protected]>
Co-authored-by: Danni <[email protected]>

Author: 3 people

packages/@react-types/shared/src/selection.d.ts

@@ -16,7 +16,7 @@ export interface SingleSelection {
   /** Whether the collection allows empty selection. */
   disallowEmptySelection?: boolean,
   /** The currently selected key in the collection (controlled). */
-  selectedKey?: Key,
+  selectedKey?: Key | null,
   /** The initial selected key in the collection (uncontrolled). */
   defaultSelectedKey?: Key,
   /** Handler that is called when the selection changes. */