Fix change notes date

Signed-off-by: Dan Bailey <danbailey@ilm.com>

Author: danrbailey

CHANGES

@@ -1,7 +1,7 @@
 OpenVDB Version History
 =======================
 
-Version 7.2.2 - February 4, 2020
+Version 7.2.2 - February 4, 2021
 
     Bug fixes:
     - Fixed a bug in the new CSG intersection merge algorithm where data

doc/changes.txt

@@ -4,7 +4,7 @@
 
 @htmlonly <a name="v7_2_2_changes"></a>@endhtmlonly
 @par
-<B>Version 7.2.2</B> - <I>February 4, 2020</I>
+<B>Version 7.2.2</B> - <I>February 4, 2021</I>
 
 @par
 Bug fixes: