Added - Virtual network rules to the list

Virtual network rules are a firewall security feature that controls whether the server for your databases and elastic pools in Azure SQL Database or for your dedicated SQL pool databases in Azure Synapse Analytics accepts communications that are sent from particular subnets in virtual networks.
Sometimes virtual network rules is the best option for securely allowing communication to the database in SQL Database and Azure Synapse Analytics.

The doc page link is: https://docs.microsoft.com/azure/azure-sql/database/vnet-service-endpoint-rule-overview?view=azuresql

Author: chenjd

articles/security/fundamentals/services-technologies.md

@@ -57,6 +57,7 @@ Over time, this list will change and grow, just as Azure does. Make sure to chec
 | [Azure SQL Always Encryption](/sql/relational-databases/security/encryption/always-encrypted-database-engine)|Protects sensitive data, such as credit card numbers or national identification numbers (for example, U.S. social security numbers), stored in Azure SQL Database or SQL Server databases.  |
 | [Azure SQL Transparent Data Encryption](/sql/relational-databases/security/encryption/transparent-data-encryption-azure-sql)| A database security feature that encrypts the storage of an entire database. |
 | [Azure SQL Database Auditing](/azure/azure-sql/database/auditing-overview)|A database auditing feature that tracks database events and writes them to an audit log in your Azure storage account.  |
+| [Virtual network rules](/azure/azure-sql/database/vnet-service-endpoint-rule-overview)|A firewall security feature that controls whether the server for your databases and elastic pools in Azure SQL Database or for your dedicated SQL pool (formerly SQL DW) databases in Azure Synapse Analytics accepts communications that are sent from particular subnets in virtual networks.  |
 
 
 ## Identity and access management