update mailer example config, remove deprecated HOST (go-gitea#30267) (go-gitea#30274)

Author: GiteaBot

docs/content/installation/with-docker.en-us.md

@@ -304,7 +304,8 @@ services:
       - GITEA__mailer__ENABLED=true
       - GITEA__mailer__FROM=${GITEA__mailer__FROM:?GITEA__mailer__FROM not set}
       - GITEA__mailer__PROTOCOL=smtps
-      - GITEA__mailer__HOST=${GITEA__mailer__HOST:?GITEA__mailer__HOST not set}
+      - GITEA__mailer__SMTP_ADDR=${GITEA__mailer__SMTP_ADDR:?GITEA__mailer__SMTP_ADDR not set}
+      - GITEA__mailer__SMTP_PORT=${GITEA__mailer__SMTP_PORT:?GITEA__mailer__SMTP_PORT not set}
       - GITEA__mailer__USER=${GITEA__mailer__USER:-apikey}
       - GITEA__mailer__PASSWD="""${GITEA__mailer__PASSWD:?GITEA__mailer__PASSWD not set}"""
 ```