Fixed documentation for period parameter (#8171)

Author: grzegorz-wolszczak

xml/System.Threading/PeriodicTimer.xml

@@ -54,7 +54,7 @@ This timer is intended to be used only by a single consumer at a time: only one
         <summary>Initializes the timer.</summary>
         <remarks>To be added.</remarks>
         <exception cref="T:System.ArgumentOutOfRangeException">
-          <paramref name="period" /> is less than or equal to 0, or greater than <see cref="F:System.UInt32.MaxValue">UInt32.MaxValue</see>.</exception>
+          <paramref name="period" /> is less than or equal to 0, or greater than or equal to <see cref="F:System.UInt32.MaxValue">UInt32.MaxValue</see>.</exception>
       </Docs>
     </Member>
     <Member MemberName="Dispose">