Add back the docs which removed by mdoc (dotnet#8120)

Author: huangmin-ms

xml/System.Web.DynamicData/DynamicFilter.xml

@@ -417,9 +417,9 @@
         <Parameter Name="source" Type="System.Linq.IQueryable" Index="0" FrameworkAlternate="netframework-4.5;netframework-4.5.1;netframework-4.5.2;netframework-4.6;netframework-4.6.1;netframework-4.6.2;netframework-4.7;netframework-4.7.1;netframework-4.7.2;netframework-4.8" />
       </Parameters>
       <Docs>
-        <param name="source">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="source">The data source query.</param>
+        <summary>Returns the filter repeater.</summary>
+        <returns>The filter.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -445,8 +445,8 @@
         <Parameter Name="dataSource" Type="System.Web.UI.WebControls.IQueryableDataSource" Index="0" FrameworkAlternate="netframework-4.5;netframework-4.5.1;netframework-4.5.2;netframework-4.6;netframework-4.6.1;netframework-4.6.2;netframework-4.7;netframework-4.7.1;netframework-4.7.2;netframework-4.8" />
       </Parameters>
       <Docs>
-        <param name="dataSource">To be added.</param>
-        <summary>To be added.</summary>
+        <param name="dataSource">The data source.</param>
+        <summary>Initializes the data source.</summary>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>

xml/System.Web.DynamicData/QueryableFilterRepeater.xml

@@ -310,9 +310,9 @@
         <Parameter Name="source" Type="System.Linq.IQueryable" Index="0" FrameworkAlternate="netframework-4.5;netframework-4.5.1;netframework-4.5.2;netframework-4.6;netframework-4.6.1;netframework-4.6.2;netframework-4.7;netframework-4.7.1;netframework-4.7.2;netframework-4.8" />
       </Parameters>
       <Docs>
-        <param name="source">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="source">The data source query.</param>
+        <summary>Returns the filter repeater.</summary>
+        <returns>The filter.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -338,8 +338,8 @@
         <Parameter Name="dataSource" Type="System.Web.UI.WebControls.IQueryableDataSource" Index="0" FrameworkAlternate="netframework-4.5;netframework-4.5.1;netframework-4.5.2;netframework-4.6;netframework-4.6.1;netframework-4.6.2;netframework-4.7;netframework-4.7.1;netframework-4.7.2;netframework-4.8" />
       </Parameters>
       <Docs>
-        <param name="dataSource">To be added.</param>
-        <summary>To be added.</summary>
+        <param name="dataSource">The data source.</param>
+        <summary>Initializes the data source.</summary>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>