Merge pull request #7812 from microsoft/tasks-instancelimit

Add instanceLimit option

Author: ntrogh

docs/editor/tasks.md

@@ -376,6 +376,7 @@ You can specify a task's run behaviors using the `runOptions` property:
 * **runOn**: Specifies when a task is run.
   * `default` - The task will only be run when executed through the **Run Task** command.
   * `folderOpen` - The task will be run when the containing folder is opened. The first time you open a folder that contains a task with `folderOpen`, you will be asked if you want to allow tasks to run automatically in that folder. You can change your decision later using the **Manage Automatic Tasks** command and selecting between **Allow Automatic Tasks** and **Disallow Automatic Tasks**.
+* **instanceLimit** - The number of instances of the task that are allowed to run simultaneously. The default value is `1`.
 
 ## Customizing auto-detected tasks