[DOCS] Add Enterprise plan note to Dynamic by Metric allocation method (#37607)

* Add Enterprise plan requirement note to Dynamic by Metric tab

* Link CCM Enterprise plan to pricing page

Author: zeinageb

content/en/cloud_cost_management/allocation/custom_allocation_rules.md

@@ -91,6 +91,8 @@ You can also specify how cost proportions should be partitioned to ensure segmen
 
 {{% tab "Dynamic by metric" %}}
 
+<div class="alert alert-info">The Dynamic by Metric allocation method requires a <a href="https://www.datadoghq.com/pricing/?product=cloud-cost-management#products">CCM Enterprise plan</a>.</div>
+
 {{< img src="cloud_cost/custom_allocation_rules/dynamic_diagram.png" alt="Diagram illustrating the dynamic by metric strategy" style="width:70%;" >}}
 
 Metrics-based allocation provides the ability to split up costs based on Datadog's [metrics queries][1]. By using performance metrics to allocate expenses, you can more accurately allocate costs based on application usage patterns.