`SliceKind::VarLen`: make doc-comment render correctly.
`SliceKind::VarLen`: make doc-comment render correctly.

(The backticks were rendering badly in VSCode.)

graydon/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust