get-started: initial refactoring

[jorgeorpinel]

• Closes docs: move /get-started index to root and /install above /get-started #747 (dedicated landing page for docs)
• Addresses part of docs: consolidate examples and higher level structure #1035 (merge get-started and tutorials sections)

[jorgeorpinel]

@shcheklein so far this only implements #747 (creates https://dvc-landing-refactor-ge-nouj86.herokuapp.com/doc) but probably a little hacky – see getItemByPath in src/utils/sidebar.js and SidebarMenu.timeout in src/components/Documentation/SidebarMenu/index.js. Can you guys look at it and lmk what a better way to implement this could be? Cc @fabiosantoscode

Also if this should be a PR of it's own I can separate it from the remaining changes (Get Started related).

[shcheklein]

Looks good to me! We should spend a bit of time to think about the landing page content (check other projects). Also, see this discussion that is relevant to your changes in the sidebar.json - #1025 (comment) ... cc @iAdramelk - if we can merge this one before Gatsby migration we might just disallow having any entry w/o index page? But to be honest I would still do redirects if file is missing, and we should be doing this on the middleware level automatically (not relying on sidebar.json).

[jorgeorpinel]

• We should spend a bit of time to think about the landing page content (check other projects)

Working on that ⏳

we need to introduce some special "Home" entry to the sidebar?

I don't think so, we have the DOC link in the top menu. But if you prefer that then sure, that wouldn't require the js code changes I did.

if we can merge this one before Gatsby migration

If you want to merge this PR soon, please approve it and I'll limit it to this first step for now.

[shcheklein]

• https://dvc-landing-refactor-ge-nouj86.herokuapp.com/doc/Home - url should be lower case
• content for the home page - probably should provide some good entry point and navigation for other sections.

[shcheklein]

I really want to get rid of changelog, make it an external link ... again a special case like a Home button ... we spend time on it again and again

[jorgeorpinel]

I thought it was an external link already before? I didn't introduce this in the Gatsby migration, just moved the order of some redirects.

[jorgeorpinel]

Let's try to address the remaining refactoring in #1074 (or further PRs)? Any problems specific to these nav order changes I can still fix here, of course.

[shcheklein]

Looks good to me! Make sure that all pages we move we make redirects from their previous locations. Feel free to merge!