Update README.md with VSCode info

Author: Dave Bartolomeo

README.md

@@ -14,3 +14,15 @@ We welcome contributions to our standard library and standard checks. Do you hav
 ## License
 
 The code in this repository is licensed under the [MIT License](LICENSE) by [GitHub](https://github.com).
+
+## Visual Studio Code integration
+
+If you use Visual Studio Code to work in this repository, there are a few integration features to make development easier.
+
+### CodeQL for Visual Studio Code
+
+You can install the [CodeQL for Visual Studio Code](https://marketplace.visualstudio.com/items?itemName=GitHub.vscode-codeql) extension to get syntax highlighting, IntelliSense, and code navigation for the QL language, as well as unit test support for testing CodeQL libraries and queries.
+
+### Tasks
+
+The `.vscode/tasks.json` file defines custom tasks specific to working in this repository. To invoke one of these tasks, select the `Terminal | Run Task...` menu option, and then select the desired task from the dropdown. You can also invoke the `Tasks: Run Task` command from the command palette.