fix broken links (#3137)

Author: mairaw

xml/System.Data.Common/DbCommand.xml

@@ -1495,7 +1495,7 @@
         <Parameter Name="cancellationToken" Type="System.Threading.CancellationToken" Index="0" FrameworkAlternate="netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="cancellationToken">An optional token to cancel the asynchronous operation. The default value is <see cref="CancellationToken.None"/>.</param>
+        <param name="cancellationToken">An optional token to cancel the asynchronous operation. The default value is <see cref="System.Threading.CancellationToken.None"/>.</param>
         <summary>Asynchronously creates a prepared (or compiled) version of the command on the data source.</summary>
         <returns>A <see cref="P:System.Threading.Tasks.Task" /> representing the asynchronous operation.</returns>
         <remarks>

xml/System.Data.Common/DbConnection.xml

@@ -294,7 +294,7 @@
         <Parameter Name="cancellationToken" Type="System.Threading.CancellationToken" Index="0" FrameworkAlternate="netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="cancellationToken">An optional token to cancel the asynchronous operation. The default value is <see cref="CancellationToken.None"/>.</param>
+        <param name="cancellationToken">An optional token to cancel the asynchronous operation. The default value is <see cref="System.Threading.CancellationToken.None"/>.</param>
         <summary>Asynchronously begins a database transaction.</summary>
         <returns>A task whose <see cref="P:System.Threading.Tasks.Task`1.Result" /> property is an object representing the new transaction.</returns>
         <remarks>
@@ -337,7 +337,7 @@
       </Parameters>
       <Docs>
         <param name="isolationLevel">One of the enumeration values that specifies the isolation level for the transaction to use.</param>
-        <param name="cancellationToken">An optional token to cancel the asynchronous operation. The default value is <see cref="CancellationToken.None"/>.</param>
+        <param name="cancellationToken">An optional token to cancel the asynchronous operation. The default value is <see cref="System.Threading.CancellationToken.None"/>.</param>
         <summary>Asynchronously begins a database transaction.</summary>
         <returns>A task whose <see cref="P:System.Threading.Tasks.Task`1.Result" /> property is an object representing the new transaction.</returns>
         <remarks>
@@ -427,7 +427,7 @@
       </Parameters>
       <Docs>
         <param name="databaseName">The name of the database for the connection to use.</param>
-        <param name="cancellationToken">An optional token to cancel the asynchronous operation. The default value is <see cref="CancellationToken.None"/>.</param>
+        <param name="cancellationToken">An optional token to cancel the asynchronous operation. The default value is <see cref="System.Threading.CancellationToken.None"/>.</param>
         <summary>Asynchronously changes the current database for an open connection.</summary>
         <returns>A task representing the asynchronous operation.</returns>
         <remarks>

xml/System.Data.Common/DbTransaction.xml

@@ -138,7 +138,7 @@
         <Parameter Name="cancellationToken" Type="System.Threading.CancellationToken" Index="0" FrameworkAlternate="netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="cancellationToken">An optional token to cancel the asynchronous operation. The default value is <see cref="CancellationToken.None"/>.</param>
+        <param name="cancellationToken">An optional token to cancel the asynchronous operation. The default value is <see cref="System.Threading.CancellationToken.None"/>.</param>
         <summary>Asynchronously commits the database transaction.</summary>
         <returns>A <see cref="P:System.Threading.Tasks.Task" /> representing the asynchronous operation.</returns>
         <remarks>
@@ -499,7 +499,7 @@
         <Parameter Name="cancellationToken" Type="System.Threading.CancellationToken" Index="0" FrameworkAlternate="netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="cancellationToken">An optional token to cancel the asynchronous operation. The default value is <see cref="CancellationToken.None"/>.</param>
+        <param name="cancellationToken">An optional token to cancel the asynchronous operation. The default value is <see cref="System.Threading.CancellationToken.None"/>.</param>
         <summary>Asynchronously rolls back a transaction from a pending state.</summary>
         <returns>A task representing the asynchronous operation.</returns>
         <remarks>