Fixed README AzureMonitorTraceExporter typo

[jeremydvoss]

Description

README previously mentioned AzureMonitorTraceExporter twice instead of just AzureMonitorTraceExporterand AzureMonitorLogExporter.

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• The pull request does not introduce [breaking changes]
• [] CHANGELOG is updated for new features, bug fixes or other significant changes.
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[rakshith91]

Thanks for the PR - LGTM