Need a way to document module namespace objects

[dmichon-msft]

Problem

API-Extractor and TSDoc support adding a documentation comment to the entry point module, but not to individual re-exported modules. Modern bundlers and other tooling vastly prefer module namespace objects over static classes because they can be fully statically analyzed and tree-shaken. However, the current model does not provide a way to apply a documentation comment to an individual module that gets applied to the module namespace object (the result of import * as ... or export * as ... expressions).

functions/foo.ts

export function foo();

functions/index.ts

export { foo } from './foo';

Functions.ts

import * as Functions from './functions/index';
// How do I put a comment on this export?
export { Functions };