Update CHANGELOG

CHANGELOG

 24.05.2018: changed counters to 1/s
 25.05.2018: a lot of code cleanup
-         packet name changed from cisco_bgp to cisco_bgp_peer
-         added support of more then one address family per peer
-           (changed item from remoteip to remoteip+familyname, rewrite of parer, inventory and check function)
+            packet name changed from cisco_bgp to cisco_bgp_peer
+            added support of more then one address family per peer
+            (changed item from remoteip to remoteip+familyname, rewrite of parer, inventory and check function)
 27.05.2018: changed scan function from  '.1.3.6.1.4.1.9.9.187.1.2.7.1.3.* to sysdecr contains cisco
 28.05.2018: changed wato, added peer alias, state if not found, infotext values
 29.05.2018: fixed longoutpout (removed not configured)
 02.11.2018: modified scanfunction (from "find 'cisco' =-1"  to "'cisco' in OID"
 02.18.2019: added fix for empty values ("" instead of "0") sugested by Laurent Barbier (lbarbier[at]arkane-studios[dot]com)
 24.02.2020: added workaround for missing cbgpPeer2AddrFamily (example L2VPN EVPN peers, Fix for jonale82[at]gmail[dot]com)
+02.03.2020: changed handling of perfdata, add only data the are really there (not None) instead of setting them to 0
\ No newline at end of file