Fix some emoji images

/cc @charliesome because I only discovered these mismatches because of
his trains

db/emoji.json

@@ -5687,6 +5687,7 @@
       "bullettrain_side"
     ]
   , "tags": [
+      "train"
     ]
   }
 , {
@@ -5696,6 +5697,7 @@
       "bullettrain_front"
     ]
   , "tags": [
+      "train"
     ]
   }
 , {