`module X : sig ... end`

Comment about X that should not appear when including X below.

`include module type of struct include X end`

Comment about X that should not appear when including X below.

`type t = int`
`module Y : sig ... end`

Top-comment of Y.

`module Y_include_synopsis : sig ... end`

The `include Y` below should have the synopsis from `Y`'s top-comment attached to it.

`module Y_include_doc : sig ... end`