Function sanitize_rust_idioms_keep_sections 

pub fn sanitize_rust_idioms_keep_sections(
    text: &str,
    target: DocTarget,
) -> String

Same as sanitize_rust_idioms but never drops rustdoc section headings.

Used by emitters that have already split the doc into sections and need to sanitise each body fragment independently (e.g. C# XML doc emission with per-section <param> / <returns> / <exception> tags).