Fix case in module name

frontend/src/components/editor/index.js

@@ -4,7 +4,7 @@ import Emphasis from "./actions/emphasis"
 import Hr from "./actions/hr"
 import Image from "./actions/image"
 import Link from "./actions/link"
-import Spoiler from "./actions/Spoiler"
+import Spoiler from "./actions/spoiler"
 import Strikethrough from "./actions/strikethrough"
 import Strong from "./actions/strong"
 import Quote from "./actions/quote"