Mention otelcol.processor.deltatocumulative in the otelcol.exporter.prometheus docs (#1227)

* Mention delta metric conversion in otelcol.exporter.prometheus docs.

* Update docs/sources/reference/components/otelcol.exporter.prometheus.md

Co-authored-by: Clayton Cornell <[email protected]>

---------

Co-authored-by: Clayton Cornell <[email protected]>

Author: ptodev

docs/sources/reference/components/otelcol.exporter.prometheus.md

@@ -93,7 +93,13 @@ are forwarded to the `forward_to` argument.
 
 The following are dropped during the conversion process:
 
-* Metrics that use the delta aggregation temporality
+* Metrics that use the delta aggregation temporality.
+  {{< admonition type="note" >}}
+  Prometheus does not natively support delta metrics.
+  If your {{< param "PRODUCT_NAME" >}} instance ingests delta OTLP metrics, you can convert them to cumulative OTLP metrics with [`otelcol.processor.deltatocumulative`][otelcol.processor.deltatocumulative] before you use `otelcol.exporter.prometheus`.
+
+  [otelcol.processor.deltatocumulative]: ../otelcol.processor.deltatocumulative
+  {{< /admonition >}}
 
 ## Component health