Document reflection load pattern in derived types

src/CodeStyle/CSharp/CodeFixes/CSharpFormattingAnalyzer.cs

@@ -10,6 +10,7 @@ internal class CSharpFormattingAnalyzer : AbstractFormattingAnalyzer
     {
         protected override Type GetAnalyzerImplType()
         {
+            // Explained at the call site in the base class
             return typeof(CSharpFormattingAnalyzerImpl);
         }
     }

src/CodeStyle/VisualBasic/CodeFixes/VisualBasicFormattingAnalyzer.vb

@@ -8,6 +8,7 @@ Namespace Microsoft.CodeAnalysis.CodeStyle
         Inherits AbstractFormattingAnalyzer
 
         Protected Overrides Function GetAnalyzerImplType() As Type
+            ' Explained at the call site in the base class
             Return GetType(VisualBasicFormattingAnalyzerImpl)
         End Function
     End Class