Add placeholder text for send testing email button in admin/config (#12452)

* Add placeholder text for send testing email button in admin/config

* Change placeholder text to expecting email address

* Localize placeholder text

* Apply suggestion from @silverwind

ok

Co-authored-by: silverwind <me@silverwind.io>

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

options/locale/locale_en-US.ini

@@ -2174,6 +2174,7 @@ config.mailer_use_sendmail = Use Sendmail
 config.mailer_sendmail_path = Sendmail Path
 config.mailer_sendmail_args = Extra Arguments to Sendmail
 config.mailer_sendmail_timeout = Sendmail Timeout
+config.test_email_placeholder = Email (e.g. test@example.com)
 config.send_test_mail = Send Testing Email
 config.test_mail_failed = Failed to send a testing email to '%s': %v
 config.test_mail_sent = A testing email has been sent to '%s'.

templates/admin/config.tmpl

@@ -237,7 +237,7 @@
 						{{.CsrfTokenHtml}}
 						<div class="inline field ui left">
 							<div class="ui input">
-								<input type="email" name="email" required>
+								<input type="email" name="email" placeholder="{{.i18n.Tr "admin.config.test_email_placeholder"}}" size="29" required>
 							</div>
 						</div>
 						<button class="ui green button" id="test-mail-btn">{{.i18n.Tr "admin.config.send_test_mail"}}</button>