Add changes file for bug 28981

The fix was in commit 61636ad989de674698601284957dacde53cc4984.

Signed-off-by: Kris Katterjohn <katterjohn@gmail.com>

changes/bug28981

@@ -0,0 +1,5 @@
+  o Minor bugfixes (misc):
+    - The amount of total available physical memory is now determined
+      using the sysctl identifier HW_PHYSMEM (rather than HW_USERMEM)
+      when it is defined and a 64-bit variant is not available.  Fixes
+      bug 28981; bugfix on 0.2.5.4-alpha.  Patch from Kris Katterjohn.