Update question about throttling

Signed-off-by: Xiaoguang Sun <[email protected]>

tidb-cloud/serverless-faqs.md

@@ -75,6 +75,10 @@ RU consumptions can occur in various scenarios. One common scenario is during ba
 
 A spike in RU usage can occur due to necessary background jobs in TiDB. These jobs, such as automatically analyzing tables and rebuilding statistics, are required for generating optimized query plans.
 
+### What are the consequences when my cluster exhausts its free quota or exceeds its spending limit?
+
+Once the free quota or spending limit of a cluster is reached, the cluster will enforce throttling measures on read and write operations. These operations will be limited until either the quota is increased or the usage is reset at the start of a new month. For more information, see [TiDB Serverless Limitations and Quotas](/tidb-cloud/serverless-limitations.md#usage-quota).
+
 ## Security FAQs
 
 ### Is my TiDB Serverless shared or dedicated?

tidb-cloud/serverless-limitations.md

@@ -63,7 +63,7 @@ For the first five TiDB Serverless clusters in your organization, TiDB Cloud pro
 
 The Request Unit (RU) is a unit of measurement used to track the resource consumption of a query or transaction. It is a metric that allows you to estimate the computational resources required to process a specific request in the database. The request unit is also the billing unit for TiDB Cloud Serverless service.
 
-Once the free quota of a cluster is reached, the read and write operations on this cluster will be throttled until you [increase the quota](/tidb-cloud/manage-serverless-spend-limit.md#update-spend-limit) or the usage is reset upon the start of a new month. For example, when the storage of a cluster exceeds 5 GiB, the maximum size limit of a single transaction is reduced from 10 MiB to 1 MiB.
+Once the free quota of a cluster is reached, the read and write operations on this cluster will be throttled until you [increase the quota](/tidb-cloud/manage-serverless-spend-limit.md#update-spend-limit) or the usage is reset upon the start of a new month.
 
 To learn more about the RU consumption of different resources (including read, write, SQL CPU, and network egress), the pricing details, and the throttled information, see [TiDB Serverless Pricing Details](https://www.pingcap.com/tidb-cloud-serverless-pricing-details).