fix(css): Rename colour gray-0 to gray-10
A tiny MVC to align the design documentation with the @gitlab-ui
gray
variable renaming from gray-0
to gray-10
as per: gitlab-org/gitlab-ui@13905a68
A tiny MVC to align the design documentation with the @gitlab-ui
gray
variable renaming from gray-0
to gray-10
as per: gitlab-org/gitlab-ui@13905a68