Andrew Winata authored 5 years ago and Evan Read committed 5 years ago

Also another factor of consideration for
runner server requirements.

This is an initiative to ensure all documentation complies completely
with the Documentation Style Guide section "Documentation is the single
source of truth (SSOT)" according to this epic
https://gitlab.com/groups/gitlab-org/-/epics/1280.

In particular, the changes of this commit touch all files under
doc/install/. Most notably:

- install/redis.md:
        Redirect to Redis section of install guide.

- install/pivotal/index.md:
        Changed its content to reflect the current status, which is no
        longer supported (since 2017!).

- install/google-protobuf.md:
        Incorporated inside installation.md under the troubleshooting section.

- install/openshift_and_gitlab.md:
        Clarified that this guide is no longer relevant. We might want to
        redirect to the Chart docs in the future.

- install/structure.md:
        Incorporated inside installation.md under its own section.

- install/kubernetes/index.md:
        Redirected to https://docs.gitlab.com/charts

Updated documentation as per latest missing features on about.gitlab.com

See merge request gitlab-org/gitlab-ee!5794

[skip ci]

[ci skip]

This updates the requirements guide to include a link to an issue where
we discuss dropping MySQL support for nested groups. This should give
users a better understanding of why we highly recommend them to use
PostgreSQL instead.

[ci skip]

This makes it more obvious that we greatly prefer PostgreSQL over
MySQL/MariaDB and that all users are recommended to use PostgreSQL
instead. This also removes the paragraph mentioning the size per user
row, as this is completely inaccurate and doesn't really help users with
anticipating the database size. Instead we now simply recommend users to
have at least 5-10 GB of storage at minimum.

[ci skip]