handle instrumentation scope in prometheus conversions

specification/metrics/datamodel.md

@@ -69,6 +69,7 @@
     + [Dropped Data Points](#dropped-data-points)
     + [Metric Attributes](#metric-attributes)
     + [Exemplars](#exemplars-2)
+    + [Instrumentation Scope](#instrumentation-scope)
     + [Resource Attributes](#resource-attributes-1)
 - [Footnotes](#footnotes)
 
@@ -1182,6 +1183,11 @@ retrieved from the `trace_id` and `span_id` label keys, respectively.  All
 labels not used for the trace and span ids MUST be added to the OpenTelemetry
 exemplar as attributes.
 
+#### Instrumentation Scope
+
+Instrumentation Scope MUST be left unset for metrics scraped from Prometheus
+endpoints.
+
 #### Resource Attributes
 
 When scraping a Prometheus endpoint, resource attributes MUST be added to the
@@ -1284,6 +1290,17 @@ OpenMetrics exemplar, and `filtered_attributes` MUST be added as labels on the
 OpenMetrics exemplar unless they would exceed the OpenMetrics
 [limit on characters](https://github.com/OpenObservability/OpenMetrics/blob/main/specification/OpenMetrics.md#exemplars).
 
+#### Instrumentation Scope
+
+The OpenMetrics equivalent of Instrumentation Scope is the
+[metric namespace](https://github.com/OpenObservability/OpenMetrics/blob/main/specification/OpenMetrics.md#metric-naming-and-namespaces),
+which is a single-word prefix for metrics which identifies the source of the
+metric. However, the Instrumentation Scope Name in OpenTelemetry isn't
+generally suitable to use as a prefix because of how verbose it is.  Exporters
+MUST not attach the instrumentation scope name as a prefix or label to metrics.
+The Instrumentation Scope MAY be added as an info-type metric family with the
+name "opentelemetry_instrumentation_scope", and labels "name" and "version".
+
 #### Resource Attributes
 
 In SDK Prometheus (pull) exporters, resource attributes SHOULD be converted to the ["target" info](https://github.com/OpenObservability/OpenMetrics/blob/main/specification/OpenMetrics.md#supporting-target-metadata-in-both-push-based-and-pull-based-systems) metric family; otherwise, they MUST be dropped, and MUST NOT be attached as labels to other metric families. The "target" info metric family MUST be an info-typed metric family whose labels MUST include the resource attributes, and MUST NOT include any other labels. There MUST be at most one "target" info metric family exposed on a Prometheus endpoint.