Add release note for vstsTask 3.0.13 (#323)

* Add release note for pipelineTask 3.0.13

* Add content for 3.0.13

* comment

releaseNotes/AzureDevOpsPipelineExtension.md

@@ -4,6 +4,9 @@ The Azure App Configuration extension in Azure DevOps pipeline has been publishe
 
 ![sample](pictures/AzureDevOpsExtensionVersionSample.PNG)
 
+### v3.0.13 - May, 04 2020
+* Fixed the issue that some symbols, for example, percent sign (%), could not be set to Pipeline Task variables correctly. [#313](https://github.com/Azure/AppConfiguration/issues/313)
+
 ### v2.0.11 - March, 24 2020
 * The Azure App Configuration pipeline task for the Azure DevOps is now generally available.
 * Added `FAQ` section to the [documentation](https://marketplace.visualstudio.com/items?itemName=AzureAppConfiguration.azure-app-configuration-task).