Update concepts-pipelines-activities.md

synapse notebook activity missing.. please validate the link format all of the over links use a relative link to a local md file however this article needs to be cross linked to the synapse pipeline documentation while the link works it might be brittle

Author: jasonhorner

articles/data-factory/concepts-pipelines-activities.md

@@ -64,6 +64,7 @@ Data transformation activity | Compute environment
 [Databricks Notebook](transform-data-databricks-notebook.md) | Azure Databricks
 [Databricks Jar Activity](transform-data-databricks-jar.md) | Azure Databricks
 [Databricks Python Activity](transform-data-databricks-python.md) | Azure Databricks
+[Synapse Notebook Activity](https://learn.microsoft.com/en-us/azure/synapse-analytics/synapse-notebook-activity) | Azure Synapse Analytics
 
 ## Control flow activities
 The following control flow activities are supported: