docs: fix minor typo (#43)

hacknug · web-flow · commit 129075424d97 · 2020-06-29T20:19:29.000+05:30
diff --git a/README.md b/README.md
@@ -55,7 +55,7 @@ plugins:[
                     sizes: '1280x720',
                     type: 'image/png',
                 },
-            ]
+            ],
             gcmSenderId: undefined,             // Optional
 
             // Standard Meta Tags
