Update Gmail mailer configuration

Author: disposedtrolley

docs/content/doc/usage/email-setup.en-us.md

@@ -76,12 +76,15 @@ The following configuration should work with GMail's SMTP server:
 ```ini
 [mailer]
 ENABLED        = true
+HOST           = smtp.gmail.com:465
 SMTP_ADDR      = smtp.gmail.com
 SMTP_PORT      = 465
-FROM           = [email protected]
-USER           = example@gmail.com
+FROM           = example.user@gmail.com
+USER           = example.user
 PASSWD         = ***
 MAILER_TYPE    = smtp
 IS_TLS_ENABLED = true
-HELO_HOSTNAME  = example.com
 ```
+
+Note that you'll need to create and use an [App password](https://support.google.com/accounts/answer/185833?hl=en) by enabling 2FA on your Google
+account. You won't be able to use your Google account password directly.