Merge pull request #2948 from github/mbg/copilot-instructions

Add initial Copilot instructions

Author: mbg

.github/copilot-instructions.md

@@ -0,0 +1,5 @@
+# CodeQL Action - Copilot Instructions
+
+The CodeQL Action is written in TypeScript and compiled to JavaScript. Both the TypeScript sources and the **generated** JavaScript code are contained in this repository. The TypeScript sources are contained in the `src` directory and the JavaScript code is contained in the `lib` directory. A GitHub Actions workflow checks that the JavaScript code in `lib` is up-to-date. Therefore, you should not review any changes to the contents of the `lib` folder and it is expected that the JavaScript code in `lib` closely mirrors the TypeScript code it is generated from.
+
+GitHub Actions workflows in the `.github/workflows` directory whose filenames start with two underscores (e.g. `__all-platform-bundle.yml`) are automatically generated using the `pr-checks/sync.sh` script from template files in the `pr-checks/checks` directory. Therefore, you do not need to review files in the `.github/workflows` directory that starts with two underscores. However, you should review changes to the `pr-checks` directory as well as workflows in the `.github/workflows` directory that do not start with underscores.