for okhttp-3.0 instrumentation, the README uses `OkHttpTracing`:
```java
import io.opentelemetry.instrumentation.okhttp.v3_0.OkHttpTracing;
...
return OkHttpTracing.builder(openTelemetry).build().newCallFactory(createClient());
```
#5624 changed `OkHttpTracing` to `OkHttpTelemetry` but the docs still
show the previous value which no longer works
* Add a README for the okhttp library instrumentation.
* Create new instrumentation for okhttp3 4.x+
This exposes a `Call.Factory` which will properly handle internal context propagation when used with async callbacks.
* update the "4.x" instrumentation to support 3.x
* Get rid of the 4.x instrumentation, and just update the 3.x instrumentation to work
* updates from PR review
* replace old reflection with method handle usage
* Apply suggestions from code review
Co-authored-by: Trask Stalnaker <trask.stalnaker@gmail.com>
Co-authored-by: Trask Stalnaker <trask.stalnaker@gmail.com>
Amir Blum
Aaron Ai
Trask Stalnaker
Martin
John Watson