Update README.md (#1281)

added how to run individual JS test

Author: angiejones

README.md

@@ -187,7 +187,9 @@ The following scripts are available for running specific tasks within the monore
 - `pnpm clear`: Runs docusaurus clear
 - `pnpm build`: Runs the production build for the site so it can be hosted by a static web server. The completed build will be in the folder `site/build`.
 - `pnpm test`: Runs the testsuites for the site and all examples, including browser tests. Requires Playwright and Java Development Kit, per installation instructions above.
-- `pnpm test:kotlin`: Runs the Kotlin testsuite only
+- `pnpm test:js`: Runs the JavaScript testsuite only.
+- `pnpm test:js myFile.test.js`: Runs the tests within `myFile.test.js` only.
+- `pnpm test:kotlin`: Runs the Kotlin testsuite only.
 - `pnpm test:rust`: Runs the Rust testsuite. Not included in the `pnpm test` lifecycle yet, only runs directly through this script.
 - `pnpm test:swift`: Runs the Swift testsuite. Not included in the `pnpm test` lifecycle yet, only runs directly through this script.