Create annotation guide for request/response handling

[etoews]

Create an annotation guide for request/response handling used in the AsyncApis.

It should have the following columns at a minimum.

| annotation | targets | purpose | example |

[etoews]

Here's a table to get us started.

https://docs.google.com/spreadsheet/ccc?key=0AvgUqtcxtxhYdHYteGJHTmVuTFB2UEtUQ3p0QndYdGc&usp=sharing

Once we've got 10 or so we'll commit them to the jclouds docs and let it grow from there.