chore(releasing): Add known issue for Datadog Metrics sink in v0.34.0 (…

…vectordotdev#19122)

* chore(releasing): Add known issue for Datadog Metrics sink in v0.34.0

Ref: vectordotdev#19110

Signed-off-by: Jesse Szwedko <jesse.szwedko@datadoghq.com>

* Update website/cue/reference/releases/0.34.0.cue

Co-authored-by: Brett Blue <84536271+brett0000FF@users.noreply.github.com>

---------

Signed-off-by: Jesse Szwedko <jesse.szwedko@datadoghq.com>
Co-authored-by: Brett Blue <84536271+brett0000FF@users.noreply.github.com>

website/cue/reference/releases/0.34.0.cue

@@ -30,6 +30,15 @@ releases: "0.34.0": {
 		be decommissioned on February 28th, 2024.
 		"""
 
+	known_issues: [
+		"""
+			The Datadog Metrics sink fails to send a large number of requests due to incorrectly
+			sized batches [#19110](https://github.com/vectordotdev/vector/issues/19110). This will
+			be fixed in v0.34.1. Until the fix is released, if you are using the Datadog Metrics
+			sink, we advise remaining on v0.33.1.
+			""",
+	]
+
 	changelog: [
 		{
 			type: "feat"