Update loadbalancing-exporter.rst

[shalk]

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Describe the change

Enter a description of the changes, why they're good for the Observability Cloud documentation, and so on.

ref https://github.com/open-telemetry/opentelemetry-collector-contrib/tree/main/exporter/loadbalancingexporter

If this contribution is time sensitive, tell us when you'd like this PR to be merged.

[aurbiztondo-splunk]

Thanks for the updates, @shalk!