Update README.md

README.md

 # SNMP uptime
 
-Monitors the uptime of a device. This is a rewrite of the original check. It will use *hrSystemUptime* if available instead of *sysUpTime*.\
-*sysUpTime* is the uptime of the snmp agent while *hrSystemUptime* it the uptime of the system.
+This check is based on the snmp_uptime check form CMK 2.0. It adds the SNMP-FRAMEWORK-MIB::snmpEngineTime OID to the check. Its value is in seconds not ticks and therefore the Uptime can now be around 68 years before a rollover of the counter :-)
+
+```
+snmpEngineTime : The number of seconds since the value of the snmpEngineBoots object last changed. When
+                 incrementing this object's value would cause it to exceed its maximum, snmpEngineBoots is
+                 incremented as if a re-initialization had occurred, and this object's value consequently
+                 reverts to zero.
+```
+
+
 
 Check Info:
 
@@ -10,8 +18,6 @@ Check Info:
 * *wato*: no change to the original check
 * *perfdata*: no change to the original check
 
-**Note**: there is a similar change in the orinial check
-
 Sample output
 
 ![sample output](/doc/sample.png?raw=true "sample [SHORT TITLE]")