Render type and not alias

[peterpeterparker]

In this PR dfinity/icp-js-canisters#1052, I created the following type:

export type SnapshotParams = Required<OptionSnapshotParams>;

However, it wasn’t rendered in the documentation. Instead, its "alias" (not sure that's the correct name) Required<OptionSnapshotParams> was. I should look into this, because I would have expected the type SnapshotParams itself to be shown.