astra_streaming_sink: minor doc improvement (#464)

Author: pgier

docs/resources/streaming_sink.md

@@ -82,7 +82,7 @@ resource "astra_streaming_sink" "streaming_sink" {
 - `processing_guarantees` (String) "ATLEAST_ONCE" "ATMOST_ONCE" "EFFECTIVELY_ONCE".
 - `retain_ordering` (Boolean) Retain ordering.
 - `sink_configs` (String) Sink Configs
-- `sink_name` (String) Name of the sink.
+- `sink_name` (String) Name of the sink. Note that the combination of tenant, namespace, and sink name must not exceed 47 characters.
 - `tenant_name` (String) Streaming tenant name.
 - `topic` (String) Streaming tenant topic.
 

internal/provider/resource_streaming_sink.go

@@ -134,7 +134,7 @@ func (r *StreamingSinkResource) Schema(_ context.Context, _ resource.SchemaReque
 				},
 			},
 			"sink_name": schema.StringAttribute{
-				Description: "Name of the sink.",
+				Description: "Name of the sink. Note that the combination of tenant, namespace, and sink name must not exceed 47 characters.",
 				Required:    true,
 				PlanModifiers: []planmodifier.String{
 					stringplanmodifier.RequiresReplace(),