Updates to docs build

[kbarros]

Still a work in progress.

[kbarros]

• Significantly reduce dependencies in docs/Project.toml
• Use unicode subscripts and superscripts instead of embedded Latex, where possible.
• Include SpinW ports with main docs.
• Remove one_dim_chain.jl from main docs. It is failing sporadically, and might fit better in SunnyContributed anyway.
• Link to local assets where possible.
• General cleanups.