Update C# version reference from 8.0 to 12.0

Author: BenjaminMichaelis

EssentialCSharp.Web/Views/Home/Home.cshtml

@@ -11,7 +11,7 @@
             <div class="h5"><i>Written by Mark Michaelis and Benjamin Michaelis with Eric Lippert & Kevin Bost</i></div>
             <p>
                 Essential C# is a well-organized, no-fluff guide to C# for programmers at all levels of experience.
-                Reflecting the most important C# features from 3.0 through 8.0 and including modern programming patterns,
+                Reflecting the most important C# features from 3.0 through 12.0 and including modern programming patterns,
                 it will help you write code that&rsquo;s simple, powerful, robust, secure, and maintainable.
             </p>
             <p>