Fix incorrect protected access modifier documentation and code comments

docs/csharp/language-reference/keywords/protected.md

@@ -26,7 +26,7 @@ A protected member of a base class is accessible in a derived class only if the
 
 [!code-csharp[csrefKeywordsModifiers#11](~/samples/snippets/csharp/VS_Snippets_VBCSharp/csrefKeywordsModifiers/CS/csrefKeywordsModifiers.cs#11)]
 
-The statement `a.x = 10` generates an error because it is made within the static method Main, and not an instance of class B.
+The statement `a.x = 10` generates an error because it accesses the protected member through a base class reference (`a` is of type `A`). Protected members can only be accessed through the derived class type or types derived from it.
 
 Struct members cannot be protected because the struct cannot be inherited.
 

samples/snippets/csharp/VS_Snippets_VBCSharp/csrefKeywordsModifiers/CS/csrefKeywordsModifiers.cs

@@ -345,8 +345,8 @@ static void Main()
             var a = new A();
             var b = new B();
 
-            // Error CS1540, because x can only be accessed by
-            // classes derived from A.
+            // Error CS1540, because x can only be accessed through
+            // the derived class type, not through the base class type.
             // a.x = 10;
 
             // OK, because this class derives from A.