CLI examples: fix date format

cli/examples/content/createVideo.json

@@ -30,7 +30,7 @@
     },
     "publishedBeforeJoystream": {
       "isPublished": true,
-      "date": "2020.02.20"
+      "date": "2012-09-27"
     }
   }
 }

cli/examples/content/updateVideo.json

@@ -30,7 +30,7 @@
     },
     "publishedBeforeJoystream": {
       "isPublished": true,
-      "date": "2020.02.20"
+      "date": "2012-09-27"
     }
   }
 }