uasyncio: README: Mention .awrite() and .aclose() methods vs asyncio.

uasyncio/README.rst

@@ -15,6 +15,7 @@ Major conceptual differences to asyncio:
 * Avoids defining a notion of Future, and especially wrapping coroutines
   in Futures, like CPython asyncio does. uasyncio works directly with
   coroutines (and callbacks).
+* Methods provided are more consistently coroutines.
 * uasyncio uses wrap-around millisecond timebase (as native to all
   MicroPython ports.)
 * Instead of single large package, number of subpackages are provided
@@ -35,3 +36,8 @@ Specific differences:
 * ``ensure_future()`` and ``Task()`` perform just scheduling operations
   and return a native coroutine, not Future/Task objects.
 * Some other functions are not (yet) implemented.
+* StreamWriter method(s) are coroutines. While in CPython asyncio,
+  StreamWriter.write() is a normal function (which potentially buffers
+  unlimited amount of data), uasyncio offers coroutine StreamWriter.awrite()
+  instead. Also, both StreamReader and StreamWriter have .aclose()
+  coroutine method.