doc: add caveat for setEvent in nested invocations

[JhaSourav07]

Description

This PR updates the JSDoc for the setEvent method in ChaincodeStub to clarify its behavior during chaincode-to-chaincode (CC2CC) invocations. As discussed in Issue #294, the current documentation does not explicitly warn developers that events can only be set from the outermost chaincode invocation.

This update ensures that the Node.js shim documentation is consistent with the Hyperledger Fabric official documentation and the Go/Java shim implementations.

Changes

• Updated libraries/fabric-shim/lib/stub.js to include a specific note regarding chaincode-to-chaincode scenarios.
• Clarified that only a single chaincode event can be included in a transaction and that if multiple calls to setEvent occur, only the last event is included.
• Added an explicit warning that events set in nested chaincode calls (e.g., if Chaincode A calls Chaincode B, and B calls setEvent) will be ignored by the peer.

Related Issue

Fixes: #294

Checklist

• Documentation updated
• Follows the project's coding standards
• Commit is signed-off (DCO)