Update pricing.mdx

Specify pricing tier for Cube Store Worker Tiers

Author: morgan-at-cube

docs/pages/product/deployment/cloud/pricing.mdx

@@ -157,6 +157,7 @@ pre-aggregations and executing queries against them under the following tiers:
 
 You can upgrade to a chosen tier in the
 <Btn>Settings</Btn> of your deployment.
+Upgrading to the M tier is only available on [Enterprise and above][cube-pricing] product tiers.
 
 ### Semantic Catalog tiers
 
@@ -367,4 +368,4 @@ product tier level. Payments are non-refundable.
 [ref-semantic-catalog]: /product/workspace/semantic-catalog
 [ref-ai-api]: /product/apis-integrations/ai-api
 [ref-ai-assistant]: /product/workspace/ai-assistant
-[ref-query-history-export]: /product/workspace/monitoring#query-history-export
+[ref-query-history-export]: /product/workspace/monitoring#query-history-export