docs: update testing commands in CONTRIBUTING.md

Author: chenjiahan

CONTRIBUTING.md

@@ -88,21 +88,27 @@ You can also run the unit tests of single package:
 pnpm run test:unit packages/core
 ```
 
-### Run artifact tests
+Update snapshots:
 
-Rslib will also verify the correctness of generated artifacts. You can run the artifact tests by executing the following command:
+```sh
+pnpm run test:unit -u
+```
+
+### Run integration tests
+
+Rslib will also verify the correctness of generated artifacts. You can run the integration tests by executing the following command:
 
 ```sh
-pnpm run test:artifact
+pnpm run test:integration
 ```
 
 If you need to run a specified test, you can add keywords to filter:
 
 ```sh
 # Only run test cases which contains `dts` keyword in file path
-pnpm test:artifact dts
+pnpm test:integration dts
 # Only run test cases which contains `dts` keyword in test name
-pnpm test:artifact -t dts
+pnpm test:integration -t dts
 ```
 
 ## Linting