This plugin displays a note icon above the current frequency, displaying a popup (or tooltip) with information about the selected frequency when clicked.
https://github.com/AmateurAudioDude/FM-DX-Webserver-Plugin-Station-Notes
Carefully read through all instructions and restart the server again after enabling the plugin for the first time.
Change take effect in real-time, bypassing the need to restart the server after each JSON file update.