Some problems from the README refactor

Some sections assumed they were all in one big README, which is no longer the case.

Some problems I found after a quick sweep:

• prepare.md has an Installation section that ends with Pick one: and no options.
• Here there's a reference to an OpenLDAP section "in this README" but no link or section in the given page.
• Here there's a link to a section on the page which doesn't exist, about Postgres replication.
• Here one of the steps links to the "Installation section below" but there is no installation section in the linked page. This same problem actually occurs a few times in that document.
• Homebrew link here is broken.

Additionally the section on testing as seen here seems to be completely missing now, and it's not clear how to run tests.

I found the testing info here: https://docs.gitlab.com/ce/development/rake_tasks.html

This is still ongoing? Confusing readme needs help!

I think it needs another refactor. I would like one page with a numbered series of instructions for Ubuntu/Debian, and another with a numbered series of instructions for CENTOS/RHEL, and another (which I'm working on) for SUSE.

There are specific issues that each platform faces that others don't. And the GDK will die in different places. I found the readme's baffling. My noob status can be useful to you because I can tell you, I didn't understand the readme, and things like the "Pick one:" that has nothing attached to it are baffling to noobs.

Here is my brain dump on how I got things going on OpenSUSE where "gdk install" died without useful console output, until I got some things sorted out, like gem install workarounds, redis-server and system-postgres isues:

https://gitlab.com/gitlab-org/gitlab-development-kit/issues/161

mentioned in merge request !259 (merged)

closed via merge request !259 (merged)