Merge branch 'patch-26' into 'master'

Update robots.txt to exclude group_members and project_members, which can expose…

See merge request gitlab-org/gitlab-ce!23463

public/robots.txt

@@ -70,3 +70,5 @@ Disallow: /*/*/hooks
 Disallow: /*/*/services
 Disallow: /*/*/protected_branches
 Disallow: /*/*/uploads/
+Disallow: /*/-/group_members
+Disallow: /*/project_members