Fix table header grammar in annotations
Fix table header grammar in annotations

Move "prefix" to out of the code backtick.

Signed-off-by: Yusuke Nakamura <116220fefe35ed3b9adea1ebb652054ad5695568@gmail.com>

opencontainers/image-spec,jonboulle/image-spec,opencontainers/image-spec,jonboulle/image-spec