[9.0](backport #9865) Add ingest-docs team as CODEOWNERS for release notes and docset.yml (#9980)

* add ingest-docs team as CODEOWNERS for release notes and docset.yml (#9865)

(cherry picked from commit c8f5f63)

# Conflicts:
#	.github/CODEOWNERS

* Update CODEOWNERS

---------

Co-authored-by: Colleen McGinnis <colleen.mcginnis@elastic.co>
Co-authored-by: Pierre HILBERT <pierre.hilbert@elastic.co>

Author: 3 people

.github/CODEOWNERS

@@ -13,5 +13,7 @@
 /deploy/helm/edot-collector @elastic/ingest-otel-data
 /deploy/kubernetes @elastic/elastic-agent-control-plane
 /dev-tools/kubernetes @elastic/elastic-agent-control-plane
+/docs/release-notes @elastic/ingest-docs
+/docs/docset.yml @elastic/ingest-docs
 /internal/pkg/agent/application/configuration_embed_changed_test.go @elastic/cloudbeat
 /internal/pkg/composable/providers/kubernetes @elastic/elastic-agent-control-plane