Add example to changeset, remove instanceof Promise check

Signed-off-by: Mark Dunphy <markd@spotify.com>

.changeset/proud-dots-fry.md

@@ -3,4 +3,35 @@
 '@backstage/plugin-catalog': minor
 ---
 
-Adds `EntityContextMenuItemBlueprint` to enable extending the entity page's context menu
+Adds `EntityContextMenuItemBlueprint` to enable extending the entity page's context menu with user defined items.
+
+For example:
+
+```ts
+import { EntityContextMenuItemBlueprint } from '@backstage/plugin-catalog-react/alpha';
+
+const myCustomHref = EntityContextMenuItemBlueprint.make({
+  name: 'test-href',
+  params: {
+    icon: <span>Example Icon</span>,
+    useProps: () => ({
+      title: 'Example Href',
+      href: '/example-path',
+      disabled: false,
+      component: 'a',
+    }),
+  },
+});
+
+const myCustomOnClick = EntityContextMenuItemBlueprint.make({
+  name: 'test-click',
+  params: {
+    icon: <span>Test Icon</span>,
+    useProps: () => ({
+      title: 'Example onClick',
+      onClick: () => window.alert('Hello world!'),
+      disabled: false,
+    }),
+  },
+});
+```

plugins/catalog-react/src/alpha/blueprints/EntityContextMenuItemBlueprint.tsx

@@ -73,8 +73,8 @@ export const EntityContextMenuItemBlueprint = createExtensionBlueprint({
         if ('onClick' in menuItemProps) {
           handleClick = () => {
             const result = menuItemProps.onClick();
-            if (result instanceof Promise) {
-              result.then(onClose);
+            if (result && 'finally' in result) {
+              result.finally(onClose);
             } else {
               onClose();
             }