corrections for 'ModifyString` flag

Author: Tanya-Solyanik

xml/System.Windows.Forms/TextFormatFlags.xml

@@ -288,7 +288,7 @@
       </ReturnValue>
       <MemberValue>65536</MemberValue>
       <Docs>
-        <summary>Has no effect on the drawn text.</summary>
+        <summary>Has no effect on the drawn text. Modifies the specified string parameter to match the displayed text if ellipsis are shown. This value has no effect unless <see cref="F:System.Windows.Forms.TextFormatFlags.EndEllipsis /> is specified.</summary>
       </Docs>
     </Member>
     <Member MemberName="NoClipping">