Pages docs



See merge request !202

Fixes pages domains abilities and group page address

The `master` can now access the pages configuration, modify domains and add certificates, but can't remove the pages.

The second bug that is fixed is the group page address. The group page project name needs to be in lowercase.

/cc @DouweM @rymai 

See merge request !195

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No need to be executable since it is sourced in /etc/init.d/gitlab

Fix markdown link



See merge request !203

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So as to be consistent with what is set in Omnibus

Don't index unnecessary data into elastic

Fixes https://dev.gitlab.org/gitlab/gitlab-ee/issues/347

See merge request !198