get-started: full refactoring

[jorgeorpinel]

Should change PR target to master branch when #1051 is merged.

• Addresses part of create a dedicated Home page for docs at dvc.org/doc (design part left) #1073 (put docs Home in /doc)
• too many sections. maybe split/combine into 3? sections (basics, pipelines, experiment mgmt)
• "the biggest potion of this is content - examples, preparing repos, writing text, etc - more than moving sections around" (from get-started: initial refactoring #1051 (comment))
• Per Get rid of CSV/TSV metrics #1097 (comment):

  ideally we should update the getting started and remove all the raw metrics and xpaths (expect metrics show).

• Per Add params #1128 (comment):

  (dvc param) should become part of the Experiments section of the new Get started tutorial

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Other questions:

• what to do with the example repo? keep as monorepo probably
  See https://github.com/iterative/example-repos-dev (which produces https://github.com/iterative/example-repos)
• extra: check and integrate with Katacoda scenarios

[casperdcl]

per #1074 (review) above

@jorgeorpinel / @shcheklein is there any way to automatically get these preview URLs in the CI? That way we could set them as the CHECK_LINKS_RELATIVE_URL (rather than https://dvc.org).

[jorgeorpinel]

Idk, maybe the Heroku integration exposes some env vars but probably not worth the effort. I can ignore it, it's just always confusing at first, and you need to check the test results every time after this to make sure nothing else is failing.

[shcheklein]

@casperdcl I think so, the problem is that we'll have to make CI script wait before we run it (for Heroku preview to be deployed)? may be we can make a separate GH action or something?

First of all we can set predictable URLs - https://devcenter.heroku.com/articles/github-integration-review-apps#selecting-the-url-pattern . Then just pull the main page with some (10 min?) timeout.

[casperdcl]

sounds good; updated #1000

[jorgeorpinel]

closing in favor of #1367