Update Exporter README.md (#5318)

* Update README.md

* Update exporter/README.md

Update per the PR comments

Co-authored-by: Alex Boten <alex@boten.ca>

* Update exporter/README.md

Update per suggestions from boten

Co-authored-by: Alex Boten <alex@boten.ca>

* Update exporter/README.md

Co-authored-by: Bogdan Drutu <lazy@splunk.com>

Co-authored-by: Alex Boten <alex@boten.ca>
Co-authored-by: Bogdan Drutu <lazy@splunk.com>

exporter/README.md

@@ -78,8 +78,10 @@ service:
 ## Data Ownership
 
 When multiple exporters are configured to send the same data (e.g. by configuring multiple
-exporters for the same pipeline) the exporters will have a shared access to the data.
-Exporters get access to this shared data when `ConsumeTraces`/`ConsumeMetrics`/`ConsumeLogs`
+exporters for the same pipeline):
+* exporters *not* configured to mutate the data will have shared access to the data
+* exporters with the Capabilities to mutate the data will receive a copy of the data
+Exporters access export data when `ConsumeTraces`/`ConsumeMetrics`/`ConsumeLogs`
 function is called. Exporters MUST NOT modify the `pdata.Traces`/`pdata.Metrics`/`pdata.Logs` argument of
 these functions. If the exporter needs to modify the data while performing the exporting
 the exporter can clone the data and perform the modification on the clone or use a