[Doc] Add the test guide document. [skip ci] (#1376)

Signed-off-by: yenuo26 <410167048@qq.com>

docs/contributing/README.md

@@ -71,14 +71,7 @@ For additional features and advanced configurations, refer to the:
 ### Testing
 
 vLLM-Omni uses `pytest` to test the codebase.
-
-```bash
-# Run all tests
-pytest tests/
-
-# Run tests for a single test file with detailed output
-pytest -s -v tests/test_omni_llm.py
-```
+Please refer to the [test instructions](./ci/test_guide.md) for detailed testing information.
 
 !!! warning
     Currently, not all unit tests pass when run on CPU platforms. If you don't have access to a GPU platform to run unit tests locally, rely on the continuous integration system to run the tests for now.
@@ -123,6 +116,9 @@ Only specific types of PRs will be reviewed. The PR title is prefixed appropriat
 !!! note
     If the PR spans more than one category, please include all relevant prefixes.
 
+### Local Test
+Please run the L1 and L2 test cases locally first and attach the results before contacting us to add the "ready" label. Please refer to the [test instructions](./ci/test_guide.md) for running the test cases.
+
 ### Code Quality
 
 The PR needs to meet the following code quality standards: