[chore] add Splunk distro to spanmetricsconnector (#29569)

Co-authored-by: Alex Boten <[email protected]>

connector/spanmetricsconnector/README.md

@@ -3,13 +3,14 @@
 <!-- status autogenerated section -->
 | Status        |           |
 | ------------- |-----------|
-| Distributions | [contrib], [grafana], [sumo] |
+| Distributions | [contrib], [grafana], [splunk], [sumo] |
 | Issues        | [![Open issues](https://img.shields.io/github/issues-search/open-telemetry/opentelemetry-collector-contrib?query=is%3Aissue%20is%3Aopen%20label%3Aconnector%2Fspanmetrics%20&label=open&color=orange&logo=opentelemetry)](https://github.com/open-telemetry/opentelemetry-collector-contrib/issues?q=is%3Aopen+is%3Aissue+label%3Aconnector%2Fspanmetrics) [![Closed issues](https://img.shields.io/github/issues-search/open-telemetry/opentelemetry-collector-contrib?query=is%3Aissue%20is%3Aclosed%20label%3Aconnector%2Fspanmetrics%20&label=closed&color=blue&logo=opentelemetry)](https://github.com/open-telemetry/opentelemetry-collector-contrib/issues?q=is%3Aclosed+is%3Aissue+label%3Aconnector%2Fspanmetrics) |
 | [Code Owners](https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/main/CONTRIBUTING.md#becoming-a-code-owner)    | [@albertteoh](https://www.github.com/albertteoh) |
 
 [alpha]: https://github.com/open-telemetry/opentelemetry-collector#alpha
 [contrib]: https://github.com/open-telemetry/opentelemetry-collector-releases/tree/main/distributions/otelcol-contrib
 [grafana]: https://github.com/grafana/agent
+[splunk]: https://github.com/signalfx/splunk-otel-collector
 [sumo]: https://github.com/SumoLogic/sumologic-otel-collector
 
 ## Supported Pipeline Types

connector/spanmetricsconnector/metadata.yaml

@@ -4,6 +4,6 @@ status:
   class: connector
   stability:
     alpha: [traces_to_metrics]
-  distributions: [contrib, sumo, grafana]
+  distributions: [contrib, sumo, grafana, splunk]
   codeowners:
     active: [albertteoh]