docs: remove the known issue in the Migrating from GA to Otelcol doc #200
Description
Please describe the question or issue you're facing with "Migrate from Grafana Agent to OpenTelemetry Collector - Observability documentation".
The Known Issues section in the doc attached mentions a known issue with Otelcol will be addressed in a PR that is mentioned. But that PR has been merged. We should update the list of known issues since this issue is no longer present.
Reported from: https://documentation.ubuntu.com/observability/latest/how-to/migrate-gagent-to-otelcol/