fix c# code example

doc/classes/String.xml

@@ -325,7 +325,7 @@
 				[/gdscript]
 				[csharp]
 				var text = "hello world";
-				var encoded = text.ToUtf8Buffer().HexEncode(); # outputs "68656c6c6f20776f726c64"
+				var encoded = text.ToUtf8Buffer().HexEncode(); // outputs "68656c6c6f20776f726c64"
 				GD.Print(buf.HexDecode().GetStringFromUtf8());
 				[/csharp]
 				[/codeblocks]

doc/classes/StringName.xml

@@ -308,7 +308,7 @@
 				[/gdscript]
 				[csharp]
 				var text = "hello world";
-				var encoded = text.ToUtf8Buffer().HexEncode(); # outputs "68656c6c6f20776f726c64"
+				var encoded = text.ToUtf8Buffer().HexEncode(); // outputs "68656c6c6f20776f726c64"
 				GD.Print(buf.HexDecode().GetStringFromUtf8());
 				[/csharp]
 				[/codeblocks]