With older versions of the RTD theme, paragraphs in nested lists would
lead to inconsistent spacing. This has been fixed, so we can remove our
workaround to use line blocks instead of paragraphs.

2 spaces is the most common indentation width used in the docs; adjust
the rest for consistency.

Also change .editorconfig accordingly.

(cherry picked from commit f1f188f8)

(cherry picked from commit c612dfba)