Add breaking change alert for ISM8 (#1477)

* ISM8 notice

Signed-off-by: lsiepel <[email protected]>

Author: lsiepel

distributions/openhab/src/main/resources/bin/update.lst

@@ -133,6 +133,9 @@ ALERT;Twitter Binding has become X. All related references to Twitter and Tweets
 [4.2.0]
 ALERT;AndroidTV Binding: The thing configuration of 'port' has been renamed and split to 'googletvPort' and 'shieldtvPort'
 
+[4.2.0]
+ALERT;ISM8 Binding: Most channels have changed and are now using Units of Measurements. Items must be adapted and the things must be recreated.
+
 [[PRE]]
 [2.2.0]
 DEFAULT;$OPENHAB_USERDATA/etc/org.ops4j.pax.logging.cfg