Add mention of email in the HTML5 notification doc

[thibaultmol]

Feedback

I started to use the integration for the first time and I was (and frankly still am) VERY confused why an html push notification integration needs my emailadres. It would be nice if the docs explained this because currently it's not even mentioned anywhere

URL

https://www.home-assistant.io/integrations/html5/

Version

2024.10.2

Additional information

No response