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.
### 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:
