docs(#577): java client docs update

[triskill]

No description provided.

[gemini-code-assist]

Code Review

This pull request updates the client libraries documentation to reflect package renames from org.zenbpm to org.pbinitiative, renames the core library artifact, and updates the Java and YAML configuration examples. Feedback suggests using a valid, stable version for the grpc-netty-shaded dependency to avoid resolution failures, and structuring the OpenTelemetry disable property as nested YAML to prevent potential Spring Boot configuration binding conflicts.

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