Update framework-developer-guide.mdx

docs/contributing/framework-developer-guide.mdx

@@ -183,7 +183,7 @@ If you need to run tests for the `extensions` module, make sure to enter `npm in
 
 The above command will run test only for the given module.
 
-### Adding a test case
+### Adding a new test case
 
 To add a test case simply add it to the `spec/<module>.spec.js` file.
 For example, if you need to add a new test case to the `debug` module, add the test case to the `spec/debug.spec.js` file.