Docs: Minor Readme update (#18438)

README.md

@@ -50,6 +50,11 @@ make run
 ```
 
 #### Frontend
+Install front-end dependencies first:
+
+```bash
+yarn install --pure-lockfile
+```
 
 Rebuild on file change, and serve them by Grafana's webserver (http://localhost:3000):
 
@@ -165,7 +170,7 @@ Follow the instructions in `./devenv` to spin up test containers running the app
 GRAFANA_TEST_DB=mysql go test ./pkg/services/sqlstore/...
 
 # Or run all the packages using the circle CI scripts. This method will be slower as the scripts will run all the tests, including the integration tests.
-./scripts/circle-test-mysql.sh 
+./scripts/circle-test-mysql.sh
 ```
 
 ```bash