Add placeholder docs structure

[sacha-l]

This PR does three things:

1. Adds the folder structure for the "docs" section.
2. Ports over all content from https://docs.substrate.io/v3/getting-started/installation and https://docs.substrate.io/v3/getting-started/windows-users/ to the docs/install page.
3. Adds slugs in the frontmatter. I'm suggesting that for content in the "docs" folder, instead of having docs.substrate.io/docs/install for example, we just have docs.substrate.io/install.

cc @nukemandan : I know you had come up with a plan to organize the installation content: I thought I'd port over what we have and you can modify it from there. ⛴ 😃

[nuke-web3]

Don't want to block this, but I think we should restructure just a bit:

[nuke-web3]

I personally think this should be more on the lines of "Development Environment Configuration" - as "Install" is a bit of a misnomer for what you are doing. Did I miss where this was discussed and decided against?

[sacha-l]

Sure.

[lisa-parity]

I intend this section to cover more than dev env set up, please stick with Install for the section title

[nuke-web3]

Should we seed all pages now with a handful of keywords that we think are core to each 1st level of the docs hierarchy? We can tweak latter on of course.
And if so, then copy these by default into higher level dirs and pages?

example here using the propper YAML syntax for items:

---
slug: /deploy
kewords:
  - deployment
  - devops
  - launch
  - CI
  - CD
  - .........
---

Another page in /deploy:

---
slug: /deploy/cloud-hosting
kewords:
  - deployment
  - devops
  - launch
  - CI
  - CD
  - AWS
  - GCS
  - GCP
  - .........
---

[lisa-parity]

TO the extent possible, yes.

[nuke-web3]

Just FAQ, not FAQ Dropbox

[nuke-web3]

IMHO this should be a sub-page of /reference:

/reference/faq

[nuke-web3]

And this page should primarily point to the stack overflow once it's ready, and maybe a few fundamentally critical FAQ that we want to highlight from there.

I would propose a /referece/troublshooting page as well that is a supplement outside the FAQ for common bugs and footguns with procedures how to fix them.

[lisa-parity]

The idea for the drop box was a free-for-all--drop any markdown file in the folder and it will get listed as a link on this page.

Agree we should have troubleshooting, but it might be in multiple sections instead of being a standalone catch-all page.

[nuke-web3]

Suggested change

	title: Substrate empowers developers
	title: Substrate Empowers Developers

Page titles in title case?

[sacha-l]

Don't think so, no see: https://docs.substrate.io/v3/contribute/writing/#punctuation on capitalization.

[nuke-web3]

All heading levels should use the following conventions: Use sentence style case.

Headings are not Titles.... are they?

[lisa-parity]

All heading levels and titles should use sentence style case.

[nuke-web3]

cc @nukemandan : I know you had come up with a plan to organize the installation content: I thought I'd port over what we have and you can modify it from there.

Yeah I had some opinions here: #514
I separated out the various bits in there except the migration /tweaking of pages content. Happy to make a new PR if you generally agree with the flow that had introduced?

[sacha-l]

cc @nukemandan : I know you had come up with a plan to organize the installation content: I thought I'd port over what we have and you can modify it from there.

Yeah I had some opinions here: #514 I separated out the various bits in there except the migration /tweaking of pages content. Happy to make a new PR if you generally agree with the flow that had introduced?

@nukemandan : All your suggestions seem valid to me. Why don't we merge this and you create a PR that focuses on this section?
For frontmatter stuff like keywords, I think it doesn't hurt to add them as you suggested. But it's also stuff that can more naturally be added once we fill up the pages with content. That's why I left them out for now.

[lisa-parity]

@nukemandan Ideally, I'd like to see a simple outline of pages under the Install heading--if you are going to take on that section--before we go off on too many tangents.

[lisa-parity]

We made a few small changes to the structure on Notion. Mostly, we are going to remove Migrate from the framework for now.

[nuke-web3]

Migrating to polkadot-developers/docs-sandbox#1