Add documentation to reboot()
Add documentation to reboot()

Signed-off-by: Zack Cerza <f801c831581d4150a2793939287636221d62131e@inktank.com>

ceph/teuthology,michaelsevilla/teuthology,SUSE/teuthology,SUSE/teuthology,caibo2014/teuthology,dmick/teuthology,robbat2/teuthology,t-miyamae/teuthology,ktdreyer/teuthology,tchaikov/teuthology,dmick/teuthology,yghannam/teuthology,ktdreyer/teuthology,michaelsevilla/teuthology,zhouyuan/teuthology,caibo2014/teuthology,ivotron/teuthology,robbat2/teuthology,t-miyamae/teuthology,ivotron/teuthology,dmick/teuthology,ceph/teuthology,tchaikov/teuthology,zhouyuan/teuthology,SUSE/teuthology,dreamhost/teuthology,yghannam/teuthology,dreamhost/teuthology