chore: update lang key

for https://github.com/NodeBB/NodeBB/issues/11675

public/language/en-GB/topic.json

@@ -185,7 +185,7 @@
 	"composer.schedule": "Schedule",
 	"composer.replying_to": "Replying to %1",
 	"composer.new_topic": "New Topic",
-	"composer.editing": "Editing",
+	"composer.editing-in": "Editing post in %1",
 
 	"composer.uploading": "uploading...",
 	"composer.thumb_url_label": "Paste a topic thumbnail URL",