Update slide_config.json

slide_config.json

@@ -11,6 +11,12 @@
             "image": "images/02_mg.png",
             "text": "This is the second slide.",
             "video": "https://www.youtube.com/embed/3JZ_D3ELwOQ"
+        },
+        {
+            "id": "slide_03",
+            "image": "images/03_mg.png",
+            "text": "This is the second slide.",
+            "video": "https://www.youtube.com/embed/3JZ_D3ELwOQ"
         }
     ]
 }