add more taskcluster.async documentation

README.md

@@ -44,6 +44,28 @@ but unnamed temporary credentials can be created regardless of your scopes.## AP
 The REST API methods are documented on
 [http://docs.taskcluster.net/](http://docs.taskcluster.net/)
 
+## Sync vs Async
+
+The objects under `taskcluster` (e.g., `taskcluster.Queue`) are python2-compatible and operate synchronously. This allows for taskcluster api access, though for bulk operations will be considerably slower... more than 10x slower in cases where you need to run many api calls that would benefit from concurrency.
+
+The objects under `taskcluster.async` (e.g., `taskcluster.async.Queue`) require `python>=3.5`. `taskcluster.async` will only be available under the python3 wheel or the source distribution; the python2 wheel will not include it. The async objects use asyncio coroutines for concurrency; this allows us to put I/O operations in the background, so operations that require the cpu can happen sooner. The code would look something like
+
+```python
+import asyncio
+from taskcluster.async import Auth
+
+async def do_ping():
+    a = Auth()
+    print(await a.ping())
+
+loop = asyncio.get_event_loop()
+loop.run_until_complete(do_ping())
+```
+
+Other async code examples are available [here](#methods-contained-in-the-client-library).
+
+Here's a slide deck for an [introduction to async python](https://gitpitch.com/escapewindow/slides-sf-2017/async-python).
+
 ## Usage
 
 * Here's a simple command:

setup.py

@@ -83,6 +83,7 @@ def run_tests(self):
         tests_require=tests_require,
         cmdclass={'test': Tox},
         zip_safe=False,
-        classifiers=['Programming Language :: Python :: 2',
-                     'Programming Language :: Python :: 3'],
+        classifiers=['Programming Language :: Python :: 2.7',
+                     'Programming Language :: Python :: 3.5',
+                     'Programming Language :: Python :: 3.6'],
     )