clarify accessibility of types returned by GetTypes and GetExported trypes, and point them to each other (dotnet#8652)

Author: IanKemp

xml/System.Reflection/Assembly.xml

@@ -1615,11 +1615,8 @@ In .NET 5 and later versions, for bundled assemblies, this property throws an ex
         <returns>An array that represents the types defined in this assembly that are visible outside the assembly.</returns>
         <remarks>
           <format type="text/markdown"><![CDATA[
-
 ## Remarks
- The only types visible outside an assembly are public types and public types nested within other public types.
-
-
+ The only types visible outside an assembly are public types and public types nested within other public types. To retrieve all types within an assembly, including those that are non-public, use the <xref:System.Reflection.Assembly.GetTypes%2A> method.
 
 ## Examples
  The following code sample defines a number of classes with various access levels, and calls <xref:System.Reflection.Assembly.GetExportedTypes%2A> to display the ones that are visible from outside the assembly.
@@ -3313,13 +3310,12 @@ Note: In <see href="https://go.microsoft.com/fwlink/?LinkID=247912">.NET for Win
       </ReturnValue>
       <Parameters />
       <Docs>
-        <summary>Gets the types defined in this assembly.</summary>
+        <summary>Gets all types defined in this assembly.</summary>
         <returns>An array that contains all the types that are defined in this assembly.</returns>
         <remarks>
           <format type="text/markdown"><![CDATA[
-
 ## Remarks
- The returned array includes nested types.
+ The returned array includes nested and non-public types. To retrieve only public types, use the <xref:System.Reflection.Assembly.GetExportedTypes%2A> method.
 
  If the <xref:System.Reflection.Assembly.GetTypes%2A> method is called on an assembly and a type in that assembly is dependent on a type in an assembly that has not been loaded (for example, if it derives from a type in the second assembly), a <xref:System.Reflection.ReflectionTypeLoadException> is thrown. For example, this can happen if the first assembly was loaded with the <xref:System.Reflection.Assembly.ReflectionOnlyLoad%2A> or <xref:System.Reflection.Assembly.ReflectionOnlyLoadFrom%2A> methods, and the second assembly was not loaded. It can also happen with assemblies loaded using the <xref:System.Reflection.Assembly.Load%2A> and <xref:System.Reflection.Assembly.LoadFile%2A> methods if the second assembly cannot be located when the <xref:System.Reflection.Assembly.GetTypes%2A> method is called.
 
@@ -3328,8 +3324,6 @@ Note: In <see href="https://go.microsoft.com/fwlink/?LinkID=247912">.NET for Win
 
  To retrieve a collection of <xref:System.Reflection.TypeInfo> objects instead of an array of <xref:System.Type> objects, use the <xref:System.Reflection.Assembly.DefinedTypes%2A?displayProperty=nameWithType> property.
 
-
-
 ## Examples
  The following example displays parameters of one method on a type in the specified assembly.