Switch to MyST and MyST-{NB} with book-theme

[krassowski]

References

Fixes #540. Also documents what is needed from kernels for new language severs to work with notebooks as discussed in https://github.com/krassowski/jupyterlab-lsp/issues/578#issuecomment-825127252 which closes #384.

Test it online: https://jupyterlab-lsp--581.org.readthedocs.build/en/581/

Code changes

• Markdown magics are now used only for paragraphs which do not include headings

User-facing changes

• Nicer docs
• A temporary logo in docs

General look and feel

Previously problematic spots as documented in #540 - now all render fine

Backwards-incompatible changes

None; the URL to Language Servers page linked in GUI stays the same.

Chores

• linted
• tested
• documented
• changelog entry

[bollwyvl]

The preview looks quite nice.

We have a lot of wide code/tables/images.... it may be worth adding a little custom css. This can be coupled with some rules to make narrative p be the traditional ~45em, but takes a little fiddling to get right... i've come up with this pattern:

@media (min-width: 1200px) {
  .container,
  .container-xl {
    max-width: 100%;
  }
}

p, .admonition {
  max-width: 48em;
}

[krassowski]

Right. Fortunately, I managed to do so with cell tags, without changing the layout:

Before:

After: