Update running-on-railway.mdx

Author: 0xflotus

content/v2/running-on-railway.mdx

@@ -29,7 +29,7 @@ The previously described method is the quickest and easiest way to get Umami up
 - Choose your forked Umami repository and select the **master** branch
 - Add a second variable called `PORT`, set its value to a valid port number (eg: `3000`). Click **Add**.
 - Add a third variable called `DATABASE_TYPE`, set its value to `postgres`. Click **Add**.
-- Add a fouth variable called `HOSTNAME`, set its value to `${{ RAILWAY_STATIC_URL }}`. Click **Add**.
+- Add a fourth variable called `HOSTNAME`, set its value to `${{ RAILWAY_STATIC_URL }}`. Click **Add**.
 - Click **Deploy**.
 
 This initial deploy will fail until you follow the rest of these steps.