Docs: Update documentation workflow and contribution guide (#2704)

Co-authored-by: Chayenne <zhaochen20@outlook.com>

test/README.md

@@ -30,3 +30,18 @@ python3 -m unittest test_openai_backend.TestOpenAIBackend.test_few_shot_qa
 # Run a suite with multiple files
 python3 run_suite.py --suite minimal
 ```
+
+## Adding or Updating Tests in CI
+
+- Create new test files under `test/srt` or `test/lang` depending on the type of test.
+- Ensure they are referenced in the respective `run_suite.py` (e.g., `test/srt/run_suite.py` or `test/lang/run_suite.py`) so they’re picked up in CI.
+- In CI, all tests run automatically. You may modify the workflows in [`.github/workflows/`](https://github.com/sgl-project/sglang/tree/main/.github/workflows) to add custom test groups or extra checks.
+
+
+## Writing Elegant Test Cases
+
+- Examine existing tests in [sglang/test](https://github.com/sgl-project/sglang/tree/main/test) for practical examples.
+- Keep each test function focused on a single scenario or piece of functionality.
+- Give tests descriptive names reflecting their purpose.
+- Use robust assertions (e.g., assert, unittest methods) to validate outcomes.
+- Clean up resources to avoid side effects and preserve test independence.