Update TimeSpan.xml (dotnet#8676)

The summary of constructor 「TimeSpan(Int32, Int32, Int32, Int32, Int32, Int32)」 should be corrected as 「Initializes a new instance of the TimeSpan structure to a specified number of days, hours, minutes, seconds, milliseconds, and microseconds.」

Author: kawa0710

xml/System/TimeSpan.xml

@@ -515,7 +515,7 @@
         <param name="seconds">Number of seconds.</param>
         <param name="milliseconds">Number of milliseconds.</param>
         <param name="microseconds">Number of microseconds.</param>
-        <summary>Initializes a new instance of the <see cref="T:System.TimeSpan" /> structure to a specified number of days, hours, minutes, seconds, and milliseconds.</summary>
+        <summary>Initializes a new instance of the <see cref="T:System.TimeSpan" /> structure to a specified number of days, hours, minutes, seconds, milliseconds, and microseconds.</summary>
         <remarks>
           <format type="text/markdown"><![CDATA[