add more course links

README.md

@@ -14,6 +14,11 @@
   - [Lesson a6: Split tests on Azure DevOps](https://cypress.tips/courses/cypress-split/lessons/a6)
   - [Lesson a7: Split tests on AWS CodeBuild](https://cypress.tips/courses/cypress-split/lessons/a7)
   - [Lesson b1: Preview the split specs](https://cypress.tips/courses/cypress-split/lessons/b1)
+  - [Lesson b2: Example splitting specs using GitHub Actions](https://cypress.tips/courses/cypress-split/lessons/b2)
+  - [Lesson b3: Use the "split" reusable workflow](https://cypress.tips/courses/cypress-split/lessons/b3)
+  - [Lesson b4: Run Cucumber specs in parallel](https://cypress.tips/courses/cypress-split/lessons/b4)
+  - [Lesson b5: Run tests in parallel against several servers](https://cypress.tips/courses/cypress-split/lessons/b5)
+  - [Lesson b6: Split specs from one subfolder](https://cypress.tips/courses/cypress-split/lessons/b6)
 - 🎓 Partially covered in my course [Cypress Plugins](https://cypress.tips/courses/cypress-plugins)
   - [Lesson m1: Run spec files in parallel using GitHub Actions](https://cypress.tips/courses/cypress-plugins/lessons/m1)
   - [Lesson m2: Run Cypress specs in parallel on CircleCI](https://cypress.tips/courses/cypress-plugins/lessons/m2)