Add note about returning returns

Making sure the API is clearer in the README for users who want to get the results from the background sampler

README.md

@@ -105,7 +105,10 @@ sampler.pause()
 sampler.resume()
 
 # Wait for the sampler to finish (up to timeout seconds)
-# sampler.wait(timeout=0.1)
+sampler.wait(timeout=0.1)
+# Note that not passing any timeout to `wait` will
+# directly save and return the results:
+idata = sampler.wait()
 
 # or we can also abort the sampler (and return the incomplete trace)
 incomplete_trace = sampler.abort()