Author: Simey Lameze
MDL-72687 assign: add missing aria-label to prev/next arrows
http://git.moodle.org/gw?p=moodle.git;a=commit;h=bff8d689151eab24af1d965666beb41dd04b4094
http://github.com/moodle/moodle/commit/bff8d689151eab24af1d965666beb41dd04b4094
+ 3.10 en [nextuser,mod_assign]
+ 3.10 en [previoususer,mod_assign]