Added some missed doc comments

src/Microsoft.AspNetCore.DataProtection/AuthenticatedEncryption/AuthenticatedEncryptorFactory.cs

@@ -11,6 +11,10 @@ using Microsoft.Extensions.Logging;
 
 namespace Microsoft.AspNetCore.DataProtection.AuthenticatedEncryption
 {
+    /// <summary>
+    /// An <see cref="IAuthenticatedEncryptorFactory"/> to create an <see cref="IAuthenticatedEncryptor"/>
+    /// based on the <see cref="AuthenticatedEncryptorConfiguration"/>.
+    /// </summary>
     public sealed class AuthenticatedEncryptorFactory : IAuthenticatedEncryptorFactory
     {
         private readonly ILoggerFactory _loggerFactory;

src/Microsoft.AspNetCore.DataProtection/AuthenticatedEncryption/CngCbcAuthenticatedEncryptorFactory.cs

@@ -12,6 +12,9 @@ using Microsoft.Extensions.Logging;
 
 namespace Microsoft.AspNetCore.DataProtection.AuthenticatedEncryption
 {
+    /// <summary>
+    /// An <see cref="IAuthenticatedEncryptorFactory"/> for <see cref="CbcAuthenticatedEncryptor"/>.
+    /// </summary>
     public sealed class CngCbcAuthenticatedEncryptorFactory : IAuthenticatedEncryptorFactory
     {
         private readonly ILogger _logger;

src/Microsoft.AspNetCore.DataProtection/AuthenticatedEncryption/CngGcmAuthenticatedEncryptorFactory.cs

@@ -12,6 +12,9 @@ using Microsoft.Extensions.Logging;
 
 namespace Microsoft.AspNetCore.DataProtection.AuthenticatedEncryption
 {
+    /// <summary>
+    /// An <see cref="IAuthenticatedEncryptorFactory"/> for <see cref="GcmAuthenticatedEncryptor"/>.
+    /// </summary>
     public sealed class CngGcmAuthenticatedEncryptorFactory : IAuthenticatedEncryptorFactory
     {
         private readonly ILogger _logger;

src/Microsoft.AspNetCore.DataProtection/AuthenticatedEncryption/ManagedAuthenticatedEncryptorFactory.cs

@@ -11,6 +11,9 @@ using Microsoft.Extensions.Logging;
 
 namespace Microsoft.AspNetCore.DataProtection.AuthenticatedEncryption
 {
+    /// <summary>
+    /// An <see cref="IAuthenticatedEncryptorFactory"/> for <see cref="ManagedAuthenticatedEncryptor"/>.
+    /// </summary>
     public sealed class ManagedAuthenticatedEncryptorFactory : IAuthenticatedEncryptorFactory
     {
         private readonly ILogger _logger;

src/Microsoft.AspNetCore.DataProtection/DataProtectionBuilderExtensions.cs

@@ -145,7 +145,7 @@ namespace Microsoft.AspNetCore.DataProtection
         /// Configures the key management options for the data protection system.
         /// </summary>
         /// <param name="builder">The <see cref="IDataProtectionBuilder"/>.</param>
-        /// <param name="setupAction">An <see cref="Action{KeyManagementOptions}"/> to configure the provided<see cref="KeyManagementOptions"/>.</param>
+        /// <param name="setupAction">An <see cref="Action{KeyManagementOptions}"/> to configure the provided <see cref="KeyManagementOptions"/>.</param>
         /// <returns>A reference to the <see cref="IDataProtectionBuilder" /> after this operation has completed.</returns>
         public static IDataProtectionBuilder AddKeyManagementOptions(this IDataProtectionBuilder builder, Action<KeyManagementOptions> setupAction)
         {