README.md in async-1.22.2 vs README.md in async-1.23.0

@@ -305,9 +305,26 @@
 
 ### Blocking Methods in Standard Library
 
 Blocking Ruby methods such as `pop` in the `Queue` class require access to their own threads and will not yield control back to the reactor which can result in a deadlock.  As a substitute for the standard library `Queue`, the `Async::Queue` class can be used.
 
+## Conventions
+
+### Nesting Tasks
+
+`Async::Barrier` and `Async::Semaphore` are designed to be compatible with each other, and with other tasks that nest `#async` invocations. There are other similar situations where you may want to pass in a parent task, e.g. `Async::IO::Endpoint#bind`.
+
+```ruby
+barrier = Async::Barrier.new
+semaphore = Async::Semaphore.new(2)
+
+semaphore.async(parent: barrier) do
+	# ...
+end
+```
+
+A `parent:` in this context is anything that responds to `#async` in the same way that `Async::Task` responds to `#async`. In situations where you strictly depend on the interface of `Async::Task`, use the `task: Task.current` pattern.
+
 ## Contributing
 
 1. Fork it
 2. Create your feature branch (`git checkout -b my-new-feature`)
 3. Commit your changes (`git commit -am 'Add some feature'`)