Added a nice comment explaining the sync call inside async function

cogs/data.py

@@ -92,6 +92,8 @@ class Data(commands.Cog):
                     }
                 )
 
+            # Temporary file must be written synchronously,
+            # otherwise it will not be there when ctx.respond() is be called
             json_write(users, Path(f"tmp/{uuid}"))
 
             await ctx.respond(file=File(Path(f"tmp/{uuid}"), filename="users.json"))