Migrate documentation: Remove docs from etcd-io/etcd

[nate-double-u]

Description

As per the conversation around the Etcd.io Docs/SEO Improvement Plan:

Replace existing documentation in etcd-io/etcd repo with signposts to new location on website (etcd.io).

Deliverable

etcd-io/etcd Documentation folder points to etcd.io/docs

Notes

• Since we agreed that issues related to the etcd.io Docs/SEO Improvement Plan should be made in the etcd-io/website repo, this issue is being created here even though it affects etcd-io/etcd

• The pull request for this issue will be made in etcd-io/etcd

• The pull request for this issue in etcd-io/etcd should not be merged until the PR for Migrate documentation: Add docs to etcd-io/website #93 has been merged. PR Migrate documentation: Add docs to etcd-io/website #99

• https://docs.google.com/spreadsheets/d/1-ZQMPc_eQ0fh1pwOHv3NltwT-ifKA5UcFePfdFiWn8I/edit?usp=sharing

[nate-double-u]

/cc @spzala @jberkus

I think removal of these docs from the etcd-io/etcd repo can go a couple ways:

1. Dex IdP model: where all the .md files were removed, and the top level documentation/README.md was altered with a note that the documentation files had moved to the website repo
2. CNI Plugins model: where each individual file that got moved was edited with a link to its new home on the website.

I'd suggest (1), but am happy to go with (2) if people prefer it. I'm also open to other suggestions.

[spzala]

/cc @xiang90 @gyuho @jingyih

[rohitdurvasula]

@nate-double-u any idea where does the etcd-mixin folder inside Documentation folder now reside ?

https://github.com/prometheus-operator/kube-prometheus used to depend on that.

[spzala]

@rohitdurvasula ah, here, https://github.com/etcd-io/website/tree/master/content/docs/current/etcd-mixin Thanks!

[nate-double-u]

If that location doesn't work and it needs to be back in this repo, let us know and we can see about restoring it. There are still a couple folders/files that have stayed in the Documentation folder here as they are a part of an automated system.

[underrun]

this breaks installs of kube-prometheus and anyone else who may have depended on that jsonnet library.

really it was never documentation... please restore it :-)

[nate-double-u]

I'll open a new PR to restore etcd-mixin shortly

[nate-double-u]

really it was never documentation...

We may want to open a separate issue at some point to move this out of the Documentation folder -- if it isn't documentation it's probably in the wrong spot.

[spzala]

@nate-double-u yeah, we should. And also, we can comment it in the files about how they are being used.