rabbitmqctl.8: Wrap a long line

... to keep it under the 80-column limit.

References #1641.

Author: dumbbell

docs/rabbitmqctl.8

@@ -449,7 +449,8 @@ Rename the node in the local database:
 .Dl rabbitmqctl rename_cluster_node rabbit@misshelpful rabbit@cordelia
 .sp
 .It
-Rename the local database directories (note, you do not need to do this if you have set the RABBITMQ_MNESIA_DIR environment variable):
+Rename the local database directories (note, you do not need to do this
+if you have set the RABBITMQ_MNESIA_DIR environment variable):
 .sp
 .Bd -literal -offset indent -compact
 mv \\