Missing XML docs in type parameter tooltips

[kerams]

These tooltips have been added in #12933. Unless I've wired something wrong, they should include XML docs (typeparam is listed as a supported tag).

/// <summary>Wrap</summary>
/// <typeparam name="a">Param</typeparam>
type Wrap<'a> =
    | Bah of 'a

Hovering over 'a will just display an icon and the parameter name. Using name="'a" is the same.