Merge branch 'tkuah-codeowners' into 'master'

Add @tkuah to CODEOWNERS

Closes gitlab-com/www-gitlab-com#3357

See merge request gitlab-org/gitlab-ce!28917

.gitlab/CODEOWNERS

 # Backend Maintainers are the default for all ruby files
-*.rb @ashmckenzie @ayufan @dbalexandre @DouweM @dzaporozhets @godfat @grzesiek @mkozono @nick.thomas @rspeicher @rymai @smcgivern @mayra-cabrera @reprazent
-*.rake @ashmckenzie @ayufan @dbalexandre @DouweM @dzaporozhets @godfat @grzesiek @mkozono @nick.thomas @rspeicher @rymai @smcgivern @mayra-cabrera @reprazent
+*.rb @ashmckenzie @ayufan @dbalexandre @DouweM @dzaporozhets @godfat @grzesiek @mkozono @mayra-cabrera @nick.thomas @rspeicher @rymai @reprazent @smcgivern @tkuah
+*.rake @ashmckenzie @ayufan @dbalexandre @DouweM @dzaporozhets @godfat @grzesiek @mkozono @mayra-cabrera @nick.thomas @rspeicher @rymai @reprazent @smcgivern @tkuah
 
 # Technical writing team are the default reviewers for everything in `doc/`
 /doc/ @axil @marcia