Fix position of intergalactic transmission in config.json (#2979)

This is sort the exercises by difficulty, then exercise name.

Author: jagdish-15

config.json

@@ -1296,6 +1296,14 @@
         ],
         "difficulty": 6
       },
+      {
+        "slug": "intergalactic-transmission",
+        "name": "Intergalactic Transmission",
+        "uuid": "b1c6dfc2-414b-45b2-9277-8b9f8bb3bcf3",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 6
+      },
       {
         "slug": "linked-list",
         "name": "Linked List",
@@ -1442,14 +1450,6 @@
         ],
         "difficulty": 6
       },
-      {
-        "slug": "intergalactic-transmission",
-        "name": "Intergalactic Transmission",
-        "uuid": "b1c6dfc2-414b-45b2-9277-8b9f8bb3bcf3",
-        "practices": [],
-        "prerequisites": [],
-        "difficulty": 6
-      },
       {
         "slug": "anagram",
         "name": "Anagram",