Apply suggestions from code review

Co-authored-by: Genevieve Warren <[email protected]>

Author: lonitra

xml/System.Windows.Forms/ToolStripItem.xml

@@ -7299,9 +7299,9 @@ If you set the <xref:System.Windows.Forms.ToolStripItem.ImageKey%2A> property, t
       <Docs>
         <summary>Occurs when the value of the <see cref="P:System.Windows.Forms.ToolStripItem.Selected" /> property changes.</summary>
         <remarks>
-          <para>This event is raised when item is selected by mouse, keyboard or programmatically.</para>
+          <para>This event is raised when an item is selected by mouse or keyboard, or programmatically.</para>
           <para>.NET Core 3.1 had removed MainMenu and MenuItem controls. ToolStripItem.SelectedChanged event</para>
-          <para>is recommended as a replacement for MenuItem.Select event.</para>
+          <para>is recommended as a replacement for the MenuItem.Select event.</para>
         </remarks>
       </Docs>
     </Member>