[DOCS] Add Nebari installation guides and getting-started as first directions

[viniciusdc]

resolves #36

I am opening this PR to gather feedback and help decide on content organization/details/etc.

This PR added the following:

• Documentation related to different Nebari install options: HPC, Cloud, and Local
• Detailed deployment guides for each supported cloud provider for Nebari Cloud
• A Getting Started section on the sidebar and menu to better direct first (admin) users on how to install Nebari and where to go after it -- please think of this as a "symlink" to better situate the first users, not as a break of the Diatexis organization
• There will also be a tutorial on how to set Local for testing (Minikube will be replaced in the future)

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[viniciusdc]

Remaining tasks:

• Fix current missing pieces from previous docs
• Populate docs with rewritten step-by-step documentation
• What level of detail should we give the user about the cloud provider options?
• Should we explain in more depth the process of generating cloud credentials besides pointing to external links/docs?
• Expand the advanced configuration
• Add explanations related to 'nebari-config.yaml'
• Expand cloud provider specific details in the yaml config

[trallard]

@trallard can you explain this? Are you asking if these "getting started" docs replace the quickstart? If so, then I'd say no, they don't. nebari-dev/nebari#18 is what I envision as the quickstart. What are your thoughts?

I am not saying that these replace the others - but the "sections" on the sidebar and the navbar - it is confusing having two sections that are seemingly the same (unless one has to go to the actual sections to see why these are different)
We still need a Nebari 101

We are following diataxis, but its very common to still have a top level "getting started" page exposed.

I am not sure I follow - these getting started sections fill in that section so not sure if we need yet another "getting started" we should have these + the Nebari 101 under the same category

For us, that actually means we need two "getting started" pages - one for an admin, and one for end user.

not really - since we are not using personas we do not need these - we need to cover the tasks these folks would need to achieve but that might mean 1, 2, 3 or as many as needed "getting started"-type docs

This is the comment I mentioned - https://github.com/nebari-dev/nebari/pull/45/files#r912518272

it is not about replacing the content but "renaming" and consolidating directories

[kcpevey]

@viniciusdc reminder to run pre-commit run --all-files one last time since new pre-commits just made it into main

[kcpevey]

From @trallard 's comments:

• Move all of your files that are in /started/* into /getting-started/*
• Nebari-101.md, quickstart.md, and the quickstart sidebar can be removed for now.
  • Nebari-101.md will be completed by this and will go into the getting-started section

[kcpevey]

Looks great! I didn't do another complete read through since I was already happy with the wordings, but I confirmed that the getting-started folder structure is in alignment with what I believe @trallard wanted to see.

[trallard]

Ok merging now. Thanks a lot @viniciusdc