Expanded upon directory exclusion for clarification
Expanded upon directory exclusion for clarification

Sentence language seemed to contradict the section header, so it's
been clarified to prevent any confusion. Also added information
about how wikis are handled during a backup.

Originally submitted at
https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/6673.

Signed-off-by: Rémy Coutable <4ea0184b9df19e0786dd00b28e6daa4d26baeb3e@rymai.me>

iiet/iiet-git,dreampet/gitlab,stoplightio/gitlabhq,jirutka/gitlabhq,dreampet/gitlab,stoplightio/gitlabhq,axilleas/gitlabhq,jirutka/gitlabhq,iiet/iiet-git,iiet/iiet-git,mmkassem/gitlabhq,dreampet/gitlab,stoplightio/gitlabhq,iiet/iiet-git,axilleas/gitlabhq,stoplightio/gitlabhq,axilleas/gitlabhq,mmkassem/gitlabhq,mmkassem/gitlabhq,jirutka/gitlabhq,jirutka/gitlabhq,dreampet/gitlab,mmkassem/gitlabhq,axilleas/gitlabhq