Basic migration of conda-store (core) docs

[pavithraes]

Address #561

Description

This pull request:

• Adds all content from old docs (i.e., docs directory) to the new structure (except the UI user-guide docs, which is outdated)
• Removes old docs from the repo?

Pull request checklist

• Did you test this change locally?
• Did you update the documentation (if required)? N/A
• Did you add/update relevant tests for this change (if required)? N/A

Additional information

Note for reviewers: This is a large PR, but the content itself does not need a review at this stage. We only need to verify that all content from docs repo have been migrated over to docusaurus-docs. I also suggest we review this over a co-working session for efficiency.

Also, note that the conda-store-ui docs have not been moved yet, and will be added in a new PR.

[netlify]

✅ Deploy Preview for kaleidoscopic-dango-0cf31d ready!

Name	Link
🔨 Latest commit	f0bf543
🔍 Latest deploy log	https://app.netlify.com/sites/kaleidoscopic-dango-0cf31d/deploys/65745e418367880009af069c
😎 Deploy Preview	https://deploy-preview-685--kaleidoscopic-dango-0cf31d.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[nkaretnikov]

Note: the "integration-test conda-store-server (pull_request)" failure is fixed here: #689