rhel: Specify that force-corefiles is enabled by default

Currently in /etc/sysconfig/openvswitch it's not clear that
force-corefiles is enabled by default.
This patch adds a comment explaining that force-corefiles is, by
default, set to yes.

Signed-off-by: Timothy Redaelli <tredaelli@redhat.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>

rhel/usr_share_openvswitch_scripts_systemd_sysconfig.template

@@ -1,6 +1,7 @@
 ### Configuration options for openvswitch
 #
-# Enable core files:
+# Enable core files.
+# This option should be set to "yes" or "no".  The default is "yes".
 # --force-corefiles=yes
 #
 # Set "nice" priority at which to run ovsdb-server: