Add missing API docs for System.Security (#4761)

* add missing API docs for System.Security

* replace xref with see cref

* Update xml/System.Security.Cryptography.X509Certificates/X509ChainPolicy.xml

Co-authored-by: Carlos Sanchez <1175054+carlossanlop@users.noreply.github.com>

* Update xml/System.Security.Cryptography.X509Certificates/X509ChainTrustMode.xml

Co-authored-by: Carlos Sanchez <1175054+carlossanlop@users.noreply.github.com>

* Update xml/System.Security.Cryptography.X509Certificates/X509ChainTrustMode.xml

Co-authored-by: Carlos Sanchez <1175054+carlossanlop@users.noreply.github.com>

* Update xml/System.Security.Cryptography.X509Certificates/X509ChainTrustMode.xml

Co-authored-by: Carlos Sanchez <1175054+carlossanlop@users.noreply.github.com>

* Update xml/System.Security.Cryptography.X509Certificates/X509ChainPolicy.xml

Co-authored-by: Carlos Sanchez <1175054+carlossanlop@users.noreply.github.com>

* Update xml/System.Security.Cryptography.X509Certificates/X509ChainPolicy.xml

Co-authored-by: Carlos Sanchez <1175054+carlossanlop@users.noreply.github.com>

* Update xml/System.Security.Cryptography.X509Certificates/X509ChainPolicy.xml

Co-authored-by: Carlos Sanchez <1175054+carlossanlop@users.noreply.github.com>

Co-authored-by: Carlos Sanchez <1175054+carlossanlop@users.noreply.github.com>

Author: krwq

xml/System.Security.Cryptography.X509Certificates/X509ChainPolicy.xml

@@ -225,9 +225,17 @@
         <ReturnType>System.Security.Cryptography.X509Certificates.X509Certificate2Collection</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <summary>Represents a collection of certificates replacing the default certificate trust.</summary>
+        <value>A collection of certificates replacing the default certificate trust.</value>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+The collection is respected only when <xref:System.Security.Cryptography.X509Certificates.X509ChainPolicy.CustomTrustStore> is set to <xref:System.Security.Cryptography.X509Certificates.X509ChainTrustMode.CustomRootTrust>.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="DisableCertificateDownloads">
@@ -489,9 +497,17 @@
         <ReturnType>System.Security.Cryptography.X509Certificates.X509ChainTrustMode</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <summary>The mode determining the root trust for building the certificate chain.</summary>
+        <value>An <see cref="T:System.Security.Cryptography.X509Certificates.X509ChainTrustMode" /> value determining the root trust.</value>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+When <xref:System.Security.Cryptography.X509Certificates.X509ChainTrustMode.CustomRootTrust> is used, the <xref:System.Security.Cryptography.X509Certificates.X509ChainPolicy.CustomTrustStore> will be used instead of the default root trust.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="UrlRetrievalTimeout">

xml/System.Security.Cryptography.X509Certificates/X509ChainTrustMode.xml

@@ -13,7 +13,7 @@
     <BaseTypeName>System.Enum</BaseTypeName>
   </Base>
   <Docs>
-    <summary>To be added.</summary>
+    <summary>The mode determining the root trust for building the certificate chain.</summary>
     <remarks>To be added.</remarks>
   </Docs>
   <Members>
@@ -34,7 +34,7 @@
       </ReturnValue>
       <MemberValue>1</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>When this value is used, the <see cref="P:System.Security.Cryptography.X509Certificates.X509ChainPolicy.CustomTrustStore" /> will be used instead of the default root trust.</summary>
       </Docs>
     </Member>
     <Member MemberName="System">
@@ -54,7 +54,7 @@
       </ReturnValue>
       <MemberValue>0</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Use the default (system) root trust.</summary>
       </Docs>
     </Member>
   </Members>

xml/System.Security.Cryptography/HashAlgorithm.xml

@@ -440,10 +440,10 @@ The following example calculates the <xref:System.Security.Cryptography.SHA256>
         <Parameter Name="cancellationToken" Type="System.Threading.CancellationToken" Index="1" FrameworkAlternate="net-5.0" />
       </Parameters>
       <Docs>
-        <param name="inputStream">To be added.</param>
-        <param name="cancellationToken">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="inputStream">The input to compute the hash code for.</param>
+        <param name="cancellationToken">The token to monitor for cancellation requests.</param>
+        <summary>Asynchronously computes the hash value for the specified <see cref="T:System.IO.Stream" /> object.</summary>
+        <returns>A task that represents the asynchronous compute hash operation and wraps the computed hash code.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>