[feature request] descriptive help text for users email address

Hi.
For me it wasn't clear why I should enter my email address for the user account, so I entered test@example.org.

At certificates I tried to add my host for "let's encrypt via http", but when I hit save I got: "Internal error" and nothing else. Whily debugging I found that the ACME challenge failed.

1. Improve the description of email address e.g. "mandatory, and will be used for let's encrypt registration"
2. "Internal error" isn't user friendly, if the acme challenge responds already(via docker log):
   [3/8/2026] [11:13:31 AM] [Express ] › ⚠ warning Saving debug log to /data/logs/letsencrypt.log
   Unable to register an account with ACME server. The ACME server believes test@example.org is an invalid email address. Please ensure it is a valid email and attempt registration again.
   Ask for help or search for solutions at https://community.letsencrypt.org. See the logfile /data/logs/letsencrypt.log or re-run Certbot with -v for more details.

If this message is returned, the user does know what went wrong.

btw. after entering the correct mail address, the registration worked perfectly.

Start at the certificate creation form and the ACME error path described in the issue; inspect the Docker logs while reproducing an invalid email registration. Done means the email field explains its Let's Encrypt use and an ACME validation failure is shown to the user instead of only as "Internal error".