[Aurantium-47]

The generated signatures still show applyEach(fns, ...args, callback) and applyEachSeries(fns, ...args, callback), although since v3 the callback belongs to the returned function. The applyEach description also still describes the old partial-application behavior. Following those signatures returns a function without starting the tasks, as reported in #1658 and #1694.

Remove the factory's callback parameter from both JSDoc entries, explain the returned function's callback and Promise forms, and add a Promise example. Runtime code is unchanged.

Validation:

• Existing applyEach tests: 8 passing, including callback, cancellation, native async functions, and Promise usage for both methods.
• ESLint for both changed files passed.
• Generated the documentation with the repository's JSDoc configuration and checked that both signatures contain only fns and ...args.
• Ran the callback and Promise forms against the public API and confirmed the functions execute only after calling the returned function.

AI assistance: OpenAI Codex helped prepare and verify this documentation change.