add devNote about unmorph downback method

Author: blkerby

region/tourian/main/Metroid Room 2.json

@@ -414,8 +414,9 @@
       "note": [
         "If Metroids are alive, minimizing damage from them requires tricky movement to manipulate them:",
         "the moonfalling option must be done starting from almost a tile to the left of the opening;",
-        "likewise, the morphing option should soft-morph about a tile to the left of the opening. "
-      ]
+        "likewise, the morphing option should soft-morph about a tile to the left of the opening."
+      ],
+      "devNote": ["FIXME: Unmorphing and downbacking through the gap can leave with more frames remaining but is more difficult."]
     },
     {
       "id": 20,