feat: add environment variable documentation and update configurations for socket port in Docker setup

webrtc-internals-exporter/webpack/webpack.config.js

@@ -1,5 +1,7 @@
 const path = require('path');
 const { EnvironmentPlugin } = require('webpack');
+const envPath = path.resolve(__dirname, '../../.env');
+const envConfig = require('dotenv').config({ path: envPath }).parsed;
 
 module.exports = (env) => {
   const url = env.URL || 'http://localhost';
@@ -25,7 +27,7 @@ module.exports = (env) => {
     },
     plugins: [
       new EnvironmentPlugin({
-        WEBRTC_INTERNALS_EXPORTER_URL: url,
+        WEBRTC_INTERNALS_EXPORTER_URL: envConfig.WEBRTC_INTERNALS_EXPORTER_URL || url
       }),
     ],
   };