doc(web-app): add setup environment variables

web-app/README.md

@@ -35,9 +35,20 @@ Then install the project dependencies by running:
 npm install
 ```
 
-Setup the environment variables in the `.env.template` file.
+Setup the environment:
+
+linux:
+```terminal
+export VUE_APP_API_KEY=your_api_key
+export VUE_APP_API_SECRET=your_api_secret
+```
+windows:
+```terminal
+# use wsl ...
+```
 
 ### Compile and run for development
+
 ```terminal
 npm run serve
 ```