add an explanation of one more great feature of zodbanalyze.

erp5/util/README.zodbanalyze.txt

@@ -5,5 +5,6 @@ This is an improved version of ZODB's ZODB/scripts/analyze.py.
 
 * faster
 * does not require Products.
+* display current/old information for each class
 * supports csv output by '-c' or '--csv'
 * supports using DBM temporary storage to limit memory usage by '-d' or '--dbm', otherwise memory usage is O(n) of number of OIDs.