Reflect maatkit -> Percona Toolkit change in documentation.

Author: Bret Martin

README

@@ -75,7 +75,7 @@ On all platform, the configuration is done with command line arguments:
 
 -m|--master             check master
 -s|--slave              check slave
--b|--heartbeat DB.TABLE table for maatkit mk-heartbeat 
+-b|--heartbeat DB.TABLE table for Percona Toolkit pt-heartbeat 
 --oid OID               registering OID
 -l|--process-list|--procs
                         enable the MySQL process list

mysql-snmp.1

@@ -76,7 +76,7 @@ adds SNMP counters for slaves
 
 .TP
 .B \-b,\-\-heartbeat DB.TABLE 
-compute slave lag with the maatkit mk-heartbeat stamp table.
+compute slave lag with the Percona Toolkit pt-heartbeat stamp table.
 
 .TP
 .B \-\-oid OID