Add Documenter docs for LabelledArrays

[00krishna]

I created the basic skeleton for the docs. The basic pieces for Documenter.jl and the github workflow Documenter.yml are created. I wanted to make sure I am on the right track before proceeding any farther.

One problem I ran into was a strange error when trying to test the development of the docs. I ran the usual code.

julia --project=docs/ docs/make.jl

But for some reason I am getting an error below. Kinda a strange error since Documenter is not imported anywhere else. Have you hit this error before? Slack #helpdesk did not turn up any clues.

WARNING: using Documenter.Documenter in module Main conflicts with an existing identifier.
ERROR: LoadError: importing Documenter into Main conflicts with an existing identifier
in expression starting at /media/hayagriva/Dropbox/sandbox/help_chris/LabelledArrays.jl/docs/make.jl:1

[ChrisRackauckas]

Can some of this be converted to docstrings?

[00krishna]

Yep, I can convert some of this to docstrings. I just wanted to make sure that the basic Documenter setup was on the right track. So I should take some of the content out of the markdown files and move it to docstrings.

I will see if I can get the CI workflow to work on my end too. That issue with importing Documenter into Main conflicts with an existing identifier prevented me from catching some of these errors before creating the PR.

[ChrisRackauckas]

Merging to start getting this into the doc builder system