Update example code, prevent naming with numbers. (#11603)

Update the example code and rename `Class1` to `MyClass`. For some programmers may learn from that and add `Class2` and `Class3` which makes their code less maintainable.

Author: Anduin2017

docs/core/tutorials/with-visual-studio-code.md

@@ -85,14 +85,14 @@ You can also watch a short video tutorial for further setup help on [Windows](ht
 ## Add a class
 
 1. To add a new class right-click in the VSCode Explorer and select **New File**. This adds a new file to the folder you have open in VSCode.
-2. Name your file `Class1.cs`. You must save it with a `.cs` extension at the end for it to be recognized as a csharp file.
+2. Name your file `MyClass.cs`. You must save it with a `.cs` extension at the end for it to be recognized as a csharp file.
 3. Add the code below to create your first class. Make sure to include the correct namespace so you can reference it from your `Program.cs` file.
 ``` csharp
 using System;
 
 namespace HelloWorld
 {
-    public class Class1
+    public class MyClass
     {
         public string ReturnMessage()
         {
@@ -113,7 +113,7 @@ namespace HelloWorld
     {
         static void Main(string[] args)
         {
-            Class1 c1 = new Class1();
+            MyClass c1 = new MyClass();
             Console.WriteLine($"Hello World! {c1.ReturnMessage()}");
         }
     }