Added update-tracker script. Updated docker build.

scripts/update-tracker.js

@@ -0,0 +1,18 @@
+require('dotenv').config();
+const fs = require('fs');
+const path = require('path');
+
+const endPoint = process.env.COLLECT_API_ENDPOINT;
+
+if (endPoint) {
+  const file = path.resolve(__dirname, '../public/umami.js');
+
+  const tracker = fs.readFileSync(file);
+
+  fs.writeFileSync(
+    path.resolve(file),
+    tracker.toString().replace(/"\/api\/collect"/g, `"${endPoint}"`),
+  );
+
+  console.log(`Updated tracker endpoint with "${endPoint}"`);
+}