Fix `LightboxGallery` style guide entry

ts/components/LightboxGallery.md

@@ -4,51 +4,31 @@ const noop = () => {};
 const messages = [
   {
     objectURL: 'https://placekitten.com/800/600',
-    attachments: [
+    attachments: [{ contentType: 'image/jpeg' }],
-      {
-        contentType: 'image/jpeg',
-      },
-    ],
   },
   {
     objectURL: 'https://placekitten.com/900/600',
-    attachments: [
+    attachments: [{ contentType: 'image/jpeg' }],
-      {
+  },
-        contentType: 'image/jpeg',
+  {
-      },
+    objectURL: 'foo.tif',
-    ],
+    attachments: [{ contentType: 'image/tiff' }],
   },
   {
     objectURL: 'https://placekitten.com/980/800',
-    attachments: [
+    attachments: [{ contentType: 'image/jpeg' }],
-      {
-        contentType: 'image/jpeg',
-      },
-    ],
   },
   {
     objectURL: 'https://placekitten.com/656/540',
-    attachments: [
+    attachments: [{ contentType: 'image/jpeg' }],
-      {
-        contentType: 'image/jpeg',
-      },
-    ],
   },
   {
     objectURL: 'https://placekitten.com/762/400',
-    attachments: [
+    attachments: [{ contentType: 'image/jpeg' }],
-      {
-        contentType: 'image/jpeg',
-      },
-    ],
   },
   {
     objectURL: 'https://placekitten.com/920/620',
-    attachments: [
+    attachments: [{ contentType: 'image/jpeg' }],
-      {
-        contentType: 'image/jpeg',
-      },
-    ],
   },
 ];