BUG: errors of margin and sidebar directives with newer docutils (0.22)

[bsipocz]

Describe the bug

There are a couple of new docutils errors showing up in the docs build, I think these are serious enough incompatibilities to hold up the new release or to add an upper pin.

/Users/bsipocz/munka/devel/executablebooks/sphinx-book-theme/docs/content/content-blocks.md:148: ERROR: The "margin" directive may not be used within topics or body elements. [docutils]
/Users/bsipocz/munka/devel/executablebooks/sphinx-book-theme/docs/content/content-blocks.md:267: ERROR: The "sidebar" directive may not be used within topics or body elements. [docutils]
/Users/bsipocz/munka/devel/executablebooks/sphinx-book-theme/docs/contributing/setup.md:42: ERROR: The "margin" directive may not be used within topics or body elements. [docutils]

Here are before and after screenshots (with docutils 0.21.2 and with 0.22.4)

Reproduce the bug

build the docs with docutils <0.22 and with >=0.22

List your environment

No response