Update Assembly HostContext, IsFullyTrusted, SecurityRuleSet properties for .NET Core/5+ behaviour

Author: elinor-fung

xml/System.Reflection.Emit/AssemblyBuilder.xml

@@ -2683,7 +2683,11 @@ The following code example shows how to define and use a dynamic assembly. The e
       </ReturnValue>
       <Docs>
         <summary>Gets the host context where the dynamic assembly is being created.</summary>
-        <value>A value that indicates the host context where the dynamic assembly is being created.</value>
+        <value>
+          .NET Framework only: A value that indicates the host context where the dynamic assembly is being created.
+
+          .NET Core and 5+: 0 in all cases.
+        </value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>

xml/System.Reflection/Assembly.xml

@@ -3628,7 +3628,11 @@ This property is marked obsolete starting in .NET 5, and generates a compile-tim
       </ReturnValue>
       <Docs>
         <summary>Gets the host context with which the assembly was loaded.</summary>
-        <value>An <see cref="T:System.Int64" /> value that indicates the host context with which the assembly was loaded, if any.</value>
+        <value>
+          .NET Framework only: An <see cref="T:System.Int64" /> value that indicates the host context with which the assembly was loaded, if any.
+
+          .NET Core and 5+: 0 in all cases.
+        </value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -3901,7 +3905,10 @@ This property is marked obsolete starting in .NET 5, and generates a compile-tim
       <Docs>
         <summary>Gets a value that indicates whether the current assembly is loaded with full trust.</summary>
         <value>
-          <see langword="true" /> if the current assembly is loaded with full trust; otherwise, <see langword="false" />.</value>
+          .NET Framework only: <see langword="true" /> if the current assembly is loaded with full trust; otherwise, <see langword="false" />.</value>
+
+          .NET Core and 5+: <see langword="true" /> in all cases.
+        </value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -6323,14 +6330,16 @@ In .NET 5 and later versions, for bundled assemblies, the value returned is an e
       </ReturnValue>
       <Docs>
         <summary>Gets a value that indicates which set of security rules the common language runtime (CLR) enforces for this assembly.</summary>
-        <value>The security rule set that the CLR enforces for this assembly.</value>
+        <value>
+          .NET Framework only: The security rule set that the CLR enforces for this assembly.
+
+          .NET Core and 5+: <xref:System.Security.SecurityRuleSet.None?displayProperty=nameWithType> in all cases.
+        </value>
         <remarks>
           <format type="text/markdown"><![CDATA[
 
 ## Remarks
- By default, assemblies that you compile with the .NET Framework 4 have [level 2](/dotnet/framework/misc/security-transparent-code-level-2) transparency, although you can explicitly make them [level 1](/dotnet/framework/misc/security-transparent-code-level-1) instead. Assemblies that were compiled with earlier versions of the .NET Framework have level 1 transparency.
-
- See [Security Changes](/dotnet/framework/security/security-changes).
+ **.NET Framework only:** By default, assemblies that you compile with the .NET Framework 4 have [level 2](/dotnet/framework/misc/security-transparent-code-level-2) transparency, although you can explicitly make them [level 1](/dotnet/framework/misc/security-transparent-code-level-1) instead. Assemblies that were compiled with earlier versions of the .NET Framework have level 1 transparency. See [Security Changes](/dotnet/framework/security/security-changes).
 
  ]]></format>
         </remarks>