added limitations

Author: richagaur

articles/cosmos-db/nosql/change-pk.md

@@ -43,6 +43,15 @@ Then, data is copied from the source container to the destination container in a
 
 Once the copy is complete, you can start using the new container with desired partition key and optionally delete the old container.
 
+
+## Limitations
+- By default, two server-side compute instances, each with 4 vCPUs and 16 GB of memory, are allocated to handle the data copy job per account. The performance of the copy job relies on various [factors](../container-copy.md#factors-that-affect-the-rate-of-a-container-copy-job). To allocate higher SKU server-side compute instances, please reach out to Microsoft support.
+- Partition key modification is supported for containers provisioned with less than 1,000,000 RU/s. For containers with over 1,000,000 provisioned throughput, please contact Microsoft support for assistance with changing the partition key.
+- Changing partition key isn't supported for accounts with following capabilities.
+   * [Disable local auth](how-to-setup-rbac.md#use-azure-resource-manager-templates)
+   * [Merge partition](merge.md)
+- The feature is currently supported only in the documented [regions](../container-copy.md#supported-regions).
+  
 ## Next Steps
 
 - Explore more about [container copy jobs](../container-copy.md).