Added instructions to run the frontend (#700)

Co-authored-by: Amir Blum <amirgiraffe@gmail.com>

CONTRIBUTING.md

@@ -7,6 +7,7 @@
   - [Local Development](#local-development)
     - [Run Odigos Cli from code](#run-odigos-cli-from-code)
     - [How to Develop Odigos Locally](#how-to-develop-odigos-locally)
+    - [How to Build and run Odigos Frontend Locally](#how-to-build-and-run-odigos-frontend-locally)
 
 Welcome! We are glad that you want to contribute to our project! 💖
 
@@ -114,14 +115,21 @@ See the [Odigos docs](https://docs.odigos.io/intro) for the full steps on debugg
 
 ### How to Build and run Odigos Frontend Locally
 
-- go to frontend folder
+- go to `frontend/webapp`
+- run:
+
+```
+ npm run build
+```
+
+- go to `frontend` folder
 - run:
 
 ```
 go build -o odigos-backend && ./odigos-backend --port 8085 --debug --address 0.0.0.0
 ```
 
-- go to webapp
+- go to `frontend/webapp`
 - run:
 
 ```