Part 3 tutorial - Creating an index page (#834)

* [learn-example][m] - code section for the tutorial part 3

* [learn-example][sm] - dont panic when no markdown.db file found

* [docs][m] - creating an inedx page

examples/learn-example/lib/mddb.ts

@@ -0,0 +1,14 @@
+import { MarkdownDB } from "@flowershow/markdowndb";
+
+const dbPath = "markdown.db";
+
+const client = new MarkdownDB({
+  client: "sqlite3",
+  connection: {
+    filename: dbPath,
+  },
+});
+
+const clientPromise = client.init();
+
+export default clientPromise;