SHOWCASE: add versioned express platform include

Author: chargome

platform-includes/getting-started-use/javascript.express__v7.mdx

@@ -0,0 +1,39 @@
+This a v7 version of the Express guide.
+
+```javascript {tabTitle:CommonJS}
+// Require this first!
+require("./instrument");
+
+// Now require other modules
+const express = require("express");
+const Sentry = require("@sentry/node");
+
+const app = express();
+
+// Add your routes, etc.
+
+// Add this after all routes,
+// but before any and other error-handling middlewares are defined
+Sentry.setupExpressErrorHandler(app);
+
+app.listen(3000);
+```
+
+```javascript {tabTitle:ESM}
+// Import this first!
+import "./instrument";
+
+// Now import other modules
+import express from "express";
+import * as Sentry from "@sentry/node";
+
+const app = express();
+
+// Add your routes, etc.
+
+// Add this after all routes,
+// but before any and other error-handling middlewares are defined
+Sentry.setupExpressErrorHandler(app);
+
+app.listen(3000);
+```