make ONLINE JavaDoc availiable. Fix README

[stargazer33]

OK, there is no working JavaDoc in IDE (see #72 ) but as a workaround - please create ONLINE JavaDoc. I really want to understand the idea behind some classes, especially the OpenAIClient.

OpenAIClient - what to do if my application is long-running and performs, let say, 10000 cals/day? The app not multi-threaded: one single thread which do /chat/completion sequentially.

Can one instance of OpenAIClient handle all these calls?
Should I create new instance for each call?
How expensive are these instances?
Should I close the OpenAIClient if my code exit? (because TCP sockets are not managed by garbage collector...)

Compare this class to okhttp3.OkHttpClient - it contains extensive JavaDoc describing things like "OkHttpClients should be shared", "Shutdown isn't necessary" etc...

Fix README:
instead of

builder.putAdditionalProperty("secret_param", JsonValue.from("4242"))

it is probably this:

builder.putAdditionalBodyProperty( "secret_param", JsonValue.from("4242"));