Note that DeserializingResourceReader should not be used with untrusted data (#12198)

* Note that DeserializingResourceReader should not be used with untrusted data

* Remove errant period after include

Author: jeffhandley

xml/System.Resources.Extensions/DeserializingResourceReader.xml

@@ -37,7 +37,15 @@
   </Interfaces>
   <Docs>
     <summary>Provides APIs similar to <see cref="T:System.Resources.ResourceReader" /> that can read and deserialize resource data written by either <see cref="T:System.Resources.ResourceWriter" /> or <see cref="T:System.Resources.Extensions.PreserializedResourceWriter" />.</summary>
-    <remarks>To be added.</remarks>
+    <remarks>
+      <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+[!INCLUDE [untrusted-data-instance-note](~/includes/untrusted-data-instance-note.md)]
+
+]]></format>
+    </remarks>
   </Docs>
   <Members>
     <Member MemberName=".ctor">

xml/System.Resources/ResourceReader.xml

@@ -107,7 +107,7 @@
 
 ## Remarks
 
-[!INCLUDE [untrusted-data-instance-note](~/includes/untrusted-data-instance-note.md)].
+[!INCLUDE [untrusted-data-instance-note](~/includes/untrusted-data-instance-note.md)]
 
  ]]></format>
         </remarks>