Begin documenting promises in more detail.
Mention that while ordering is not defined, a best effort at FIFO is made in the usual case.
Fix (English) grammar by removing duplicated verb.
Document promise::set_exception and make sure the documentation format of promise::set is in line with promise::set_exception.
Use the right quotes for inline code documentation.
Document basic future access.
Document shared methods on promise/future.
Add declaration of no-arg new_promise() function.
Proofreading fixes.
Describe future/promise callbacks.
Add error handling to future callback example, to prevent reader confusion.
Describe chaining/composing of promises.