Update README

Author: chingc

README.md

@@ -209,6 +209,7 @@ See the workflows:
 - [GitHub Actions: Adding a log annotation](https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/workflow-commands-for-github-actions#setting-a-notice-message)
 - [GitHub Actions: Adding a system path](https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/workflow-commands-for-github-actions#adding-a-system-path)
 - [GitHub Actions: Caching dependencies to speed up workflows](https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/caching-dependencies-to-speed-up-workflows)
+- [GitHub Actions: Evaluate expressions in workflows and actions]https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/evaluate-expressions-in-workflows-and-actions
 - [GitHub Actions: Events that trigger workflows](https://docs.github.com/en/actions/writing-workflows/choosing-when-your-workflow-runs/events-that-trigger-workflows)
 - [GitHub Actions: Running variations of jobs in a workflow](https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/running-variations-of-jobs-in-a-workflow)
 - [GitHub Actions: Setting an environment variable](https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/workflow-commands-for-github-actions#setting-an-environment-variable)