chore(docs): installing-superset-from-scratch guide gets complete, orderly

[AlphaJack]

Now guide can be followed directly: venv is the only Python environment mentioned, needed environmental variables are stored on a file and sourced from there. All superset commands can now be run without interruptions

SUMMARY

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[github-actions]

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[sfirke]

This looks like a wonderful PR! People get tripped up by these steps and the way you reordered and added necessary config variables should help a lot. It looks good to me, but I have never actually installed Superset from scratch (I only have deployed with Docker) so don't feel qualified to merge it myself. Hopefully someone else can take a quick peek, agrees with me, and we can merge ASAP.

[sfirke]

suggested one comment re: importance of not losing your secret key

[AlphaJack]

@sfirke Based on the "Installing from Scratch" guide I created superset-venv, an AUR package for Arch Linux users.

Unfortunately it was not possible to create a non-venv superset, as the app requires specific dependency versions, either too old or not yet available from Arch repos.

In both packages I included a message with the manual steps needed to finalize the installation.

[rusackas]

I think the file this was editing is no longer there, as things got shuffled around a bit. This needs a rebase, but might also need additional tweaking after doing so. I'll convert it to a draft for the moment since it's not mergeable, but I hopeful that we can merge it soon if updates are made :) Thanks for the patience... we drowned in PRs for a bit, and are just coming around to some loose ends.

[sfirke]

Doh, I didn't remember this when I made #28221 which overlaps heavily with this one. We can probably tackle both together.