Fixes #42858

Add an explanation on declaring variables in top level statements.

Author: BillWagner

docs/csharp/tutorials/top-level-statements.md

@@ -100,6 +100,8 @@ Should I use top level statements in all my programs?
 Better not tell you now.
 ```
 
+The code to generate an answer includes a variable declaration in your top level statements. The compiler includes that declaration in the compiler generated `Main` method. Because these variable declarations are local variables, you can't include the `static` modifier.
+
 This code answers the questions, but let's add one more feature. You'd like your question app to simulate thinking about the answer. You can do that by adding a bit of ASCII animation, and pausing while working. Add the following code after the line that echoes the question:
 
 :::code language="csharp" source="snippets/top-level-statements/UtilitiesPassOne.cs" ID="AnimationFirstPass":::