core: Adds task description for SshSoftFencingCommand

Adds task description for SshSoftFencingCommand.

Change-Id: I7a217f52f9558fc781a326fb8b34a040fdd44563
Bug-Url: https://bugzilla.redhat.com/988305
Signed-off-by: Martin Perina <mperina@redhat.com>