(TK-117) Add external API docs

Add some external API docs in the doc folder which detail how
to make requests using the Java and clojure clients.
I think it would be good to point out that the caller, when finished using the client, is required to make a `close` call in order to have the client and all resources associated with it cleaned up.  There is no implicit cleanup done for the associated resources when a client instance falls out of scope and is garbage collected.  Also, once a `close` call is made on the client instance, no further requests can be made on the client instance.