Fix File.Move exceptions (#3865)

Author: nxtn

xml/System.IO/File.xml

@@ -2475,11 +2475,12 @@ The following example moves a file.
 
           ]]></format>
         </remarks>
-        <exception cref="T:System.IO.IOException">The destination file already exists.  
-  
- -or-  
-  
- <paramref name="sourceFileName" /> was not found.</exception>
+        <exception cref="T:System.IO.IOException">
+          <paramref name="destFileName" /> already exists.
+        </exception>
+        <exception cref="T:System.IO.FileNotFoundException">
+          <paramref name="sourceFileName" /> was not found.
+        </exception>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="sourceFileName" /> or <paramref name="destFileName" /> is <see langword="null" />.</exception>
         <exception cref="T:System.ArgumentException">
@@ -2552,6 +2553,9 @@ The following example moves a file.
           ]]></format>
         </remarks>
         <exception cref="T:System.IO.IOException">
+          <paramref name="destFileName" /> already exists and <paramref name="overwrite" /> is <see langword="false" />.
+        </exception>
+        <exception cref="T:System.IO.FileNotFoundException">
           <paramref name="sourceFileName" /> was not found.</exception>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="sourceFileName" /> or <paramref name="destFileName" /> is <see langword="null" />.</exception>