Git commits in Moodle 3.6.4 by Thomas Korner

commit 0553a6d90c054e33b0da79abd68edbe6be381892
Author: Thomas Korner <thomas.korner@let.ethz.ch>
Date:   Fri, 05 Apr 2019 19:56:09 +0800
Tag:    v3.6.4

MDL-65279 core: typo in categoriesandcourses fixed