WPForms: add field description in notification HTML and plain text emails

// HTML Email.

add_filter( 'wpforms_html_field_value', static function ( $field_val, $field, $form_data, $context ) {

	if ( $context !== 'email-html' ) {

		return $field_val;

	}

	if ( empty( $form_data['fields'][ $field['id'] ] ) ) {

		return $field_val;

	}

	$field_data = $form_data['fields'][ $field['id'] ];

	if ( empty( $field_data['description'] ) ) {

		return $field_val;

	}

	return $field_val . '<p style="padding:5px;background-color:yellow;"><i>' . $field_data['description'] . '</i></p>';

}, 10, 4 );

// Plain text email.

add_filter( 'wpforms_plaintext_field_value', static function ( $field_val, $field, $form_data ) {

	if ( empty( $form_data['fields'][ $field['id'] ] ) ) {

		return $field_val;

	}

	$field_data = $form_data['fields'][ $field['id'] ];

	if ( empty( $field_data['description'] ) ) {

		return $field_val;

	}

	$field_val = str_replace( [ "\r", "\n" ], '', $field_val );

	return $field_val . "\r\n" . $field_data['description'] . "\r\n\r\n";

}, 10, 3 );