Pluralise expiry strings (#499)

Author: mdjnelson

element/expiry/lang/en/customcertelement_expiry.php

@@ -35,11 +35,11 @@
 $string['enrolmentenddate'] = 'Enrolment end date';
 $string['enrolmentstartdate'] = 'Enrolment start date';
 $string['expireson'] = 'Expires on';
-$string['expirydatefive'] = 'Expiry date (5 year)';
-$string['expirydatefour'] = 'Expiry date (4 year)';
+$string['expirydatefive'] = 'Expiry date (5 years)';
+$string['expirydatefour'] = 'Expiry date (4 years)';
 $string['expirydateone'] = 'Expiry date (1 year)';
-$string['expirydatethree'] = 'Expiry date (3 year)';
-$string['expirydatetwo'] = 'Expiry date (2 year)';
+$string['expirydatethree'] = 'Expiry date (3 years)';
+$string['expirydatetwo'] = 'Expiry date (2 years)';
 $string['issueddate'] = 'Issued date';
 $string['numbersuffix_nd_as_in_second'] = 'nd';
 $string['numbersuffix_rd_as_in_third'] = 'rd';