MediaTypeNames+Application - update documentation (#4324)

* MediaTypeNames+Application - update documentation

* Apply suggestions from code review

Co-authored-by: Karel Zikmund <karelz@microsoft.com>

Co-authored-by: Jan Jahoda <jajahoda@.microsoft.com>
Co-authored-by: Karel Zikmund <karelz@microsoft.com>

Author: 3 people

xml/System.Net.Mime/MediaTypeNames+Application.xml

@@ -64,7 +64,7 @@
         <ReturnType>System.String</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Specifies that the <see cref="T:System.Net.Mime.MediaTypeNames.Application" /> data is in JSON format.</summary>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -233,7 +233,7 @@
         <ReturnType>System.String</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Specifies that the <see cref="T:System.Net.Mime.MediaTypeNames.Application" /> data is in XML format.</summary>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>