added using_custom_fonts example

using_custom_fonts/lib/main.dart

@@ -0,0 +1,23 @@
+import 'package:flutter/material.dart';
+
+void main() {
+  runApp(new MaterialApp(
+    // Title
+      title: "Using Custom Fonts",
+      // Home
+      home: new Scaffold(
+        // Appbar
+        appBar: new AppBar(
+          // Title
+          title: new Text("Using Custom Fonts"),
+        ),
+        // Body
+        body: new Container(
+          // Center the content
+          child: new Center(
+            // Add Text
+            child: new Text("The quick brown fox jumps over the lazy dog"),
+          ),
+        ),
+      )));
+}