Fix myst sphinx warnings

[stevepiercy]

This PR uses the branch add-myst-sphinx-config to build the docs for testing. This PR should be merged into #3032 before the other is merged into plone6-docs

[stevepiercy]

Quick syntax question for y'all. I'm working on fixing the jsx Sphinx highlighting, and the parser is super picky. This does not parse:

<SidebarPortal selected={this.props.selected}>
  <InlineForm
    icon={<Icon size="24px" name={nameSVG} />}
    schema={schema}
    title={schema.title}
    headerActions={<button onClick={() => {}}>Action</button>}
    footer={<div>I'm footer</div>}
    onChangeField={(id, value) => {
      this.props.onChangeBlock(this.props.block, {
        ...this.props.data,
        [id]: value,
      });
    }}
    formData={this.props.data}
  />
</SidebarPortal>;

...but if I quote the HTML values, then it does parse:

<SidebarPortal selected={this.props.selected}>
  <InlineForm
    icon={"<Icon size="24px" name={nameSVG} />"}
    schema={schema}
    title={schema.title}
    headerActions={"<button onClick={() => {}}>Action</button>"}
    footer={"<div>I'm footer</div>"}
    onChangeField={(id, value) => {
      this.props.onChangeBlock(this.props.block, {
        ...this.props.data,
        [id]: value,
      });
    }}
    formData={this.props.data}
  />
</SidebarPortal>;

My question is whether the latter form is valid syntax when actually used as code? It would be great if someone could run a quick test for me, perhaps a simple return <h1>hello</h1> and return "<h1>hello</h1>" to compare?

To go along with this, we need to make a choice about sytnax highlighting for jsx.

1. Quote HTML values
2. Leave as is, and ignore lack of syntax highlighting for many jsx code blocks
3. Submit a PR to fix the parser

[tiberiuichim]

@stevepiercy no, something={"myfunc()"} binds the something parameter to a string, it doesn't execute myfunc(). Maybe we can use simple js syntax highlighting? Would it work? IMHO we could even live without highlighting, if there's no other way.

[stevepiercy]

I reverted those incorrect "fixes".

I opened an issue here #3038 and fcurella/jsx-lexer#15

js as the lexer also fails.

We can do without syntax highlighting for now, but someone who understands the lexer and jsx syntax should submit a PR to the project.

[stevepiercy]

It turns out that jsx-lexer does not like ' within HTML tags. sheesh!

[stevepiercy]

This PR is now ready for final review. Any takers?