Outdated third party logging documentation

Issue in /src/pages/guides/using/logging_monitoring.md
`I/O Runtime doesn’t offer a configuration to send activations and logs to an external system, something like Splunk, Datadog or New Relic. This is something we are considering to offer in the future.`

We do support Splunk and Azure Logs: https://developer.adobe.com/app-builder/docs/guides/application_logging/#forwarding-application-logs
New Relic support is a feature request: https://github.com/adobe/aio-cli/issues/348

Open /src/pages/guides/using/logging_monitoring.md and compare the outdated statement with the forwarding-application-logs documentation. Update the logging support information to reflect Splunk and Azure Logs, while preserving the note that New Relic support is a feature request. Done means the guide no longer claims external logging is unsupported.

Written by the indexing model from the issue text.