Document interface requirements.

Author: ioquatix

lib/io/stream/readable.rb

@@ -22,6 +22,8 @@ module IO::Stream
 	MAXIMUM_READ_SIZE = ENV.fetch("IO_STREAM_MAXIMUM_READ_SIZE", MINIMUM_READ_SIZE * 64).to_i
 
 	# A module providing readable stream functionality.
+	#
+	# You must implement the `sysread` method to read data from the underlying IO.
 	module Readable
 		def initialize(minimum_read_size: MINIMUM_READ_SIZE, maximum_read_size: MAXIMUM_READ_SIZE, block_size: nil, **, &block)
 			@done = false

lib/io/stream/writable.rb

@@ -10,6 +10,8 @@ module IO::Stream
 	MINIMUM_WRITE_SIZE = ENV.fetch("IO_STREAM_MINIMUM_WRITE_SIZE", BLOCK_SIZE).to_i
 
 	# A module providing writable stream functionality.
+	#
+	# You must implement the `syswrite` method to write data to the underlying IO.
 	module Writable
 		def initialize(minimum_write_size: MINIMUM_WRITE_SIZE, **, &block)
 			@writing = ::Thread::Mutex.new