Package Setup

[lkdvos]

Here I add the setup to convert this into a self-standing package. Some remarks:

• Should this include a dedicated docs page, or does an explanation + example in the README suffice?

To do

• docstrings
• example
• more tests (in particular for special shape combinations)

[mtfishman]

Should this include a dedicated docs page, or does an explanation + example in the README suffice?

Something we could do is define an examples/README.jl in the Literate.jl format, use that to generate a docs/src/index.md file to be the splash page for the docs, and then the README.md can just be a link to docs/src/index.md (https://github.com/ITensor/ITensors.jl/blob/main/README.md). Then we don't have to choose :). (I think we can create that as a workflow in docs/makedocs.jl to make it automated though I haven't tried that yet.)

[mtfishman]

This is outdated since it was superseded by #2, I'll close though we probably have to update this package to reflect changes to ITensorPkgSkeleton.jl.