Add one-sentence summary to management section
Add one-sentence summary to management section

This makes viewing the docbook-generated chunk associated with the
management section a bit less disorienting.  Modeled on the approach
taken by the PostgreSQL manual.

nvoron23/titan,jankotek/titan,tomersagi/titan,mbrukman/titan,jamestyack/titan,qiuqiyuan/titan,graben1437/titan,amcp/titan,mbrukman/titan,elubow/titan,englishtown/titan,kangkot/titan,elkingtonmcb/titan,pluradj/titan,kangkot/titan,wangbf/titan,ThiagoGarciaAlves/titan,kalatestimine/titan,kangkot/titan,hortonworks/titan,banjiewen/titan,elkingtonmcb/titan,dylanht/titan,xlcupid/titan,hortonworks/titan,kalatestimine/titan,jamestyack/titan,CYPP/titan,graben1437/titan,dylanht/titan,mwpnava/titan,nvoron23/titan,anuragkh/titan,qiuqiyuan/titan,evanv/titan,fengshao0907/titan,tomersagi/titan,qiuqiyuan/titan,hortonworks/titan,mwpnava/titan,jamestyack/titan,elubow/titan,mwpnava/titan,xlcupid/titan,amcp/titan,samanalysis/titan,englishtown/titan,pluradj/titan,pluradj/titan,qiuqiyuan/titan,mbrukman/titan,elkingtonmcb/titan,evanv/titan,mwpnava/titan,dylanht/titan,ThiagoGarciaAlves/titan,anuragkh/titan,graben1437/titan,thinkaurelius/titan,fengshao0907/titan,wangbf/titan,CYPP/titan,ThiagoGarciaAlves/titan,fengshao0907/titan,tomersagi/titan,jankotek/titan,ThiagoGarciaAlves/titan,anuragkh/titan,amcp/titan,tomersagi/titan,hortonworks/titan,thinkaurelius/titan,pluradj/titan,qiuqiyuan/titan,wangbf/titan,jankotek/titan,elubow/titan,englishtown/titan,amcp/titan,kalatestimine/titan,anuragkh/titan,elkingtonmcb/titan,englishtown/titan,elkingtonmcb/titan,jamestyack/titan,wangbf/titan,evanv/titan,thinkaurelius/titan,samanalysis/titan,jankotek/titan,kangkot/titan,fengshao0907/titan,nvoron23/titan,evanv/titan,evanv/titan,dylanht/titan,samanalysis/titan,jankotek/titan,banjiewen/titan,xlcupid/titan,CYPP/titan,mbrukman/titan,xlcupid/titan,banjiewen/titan,CYPP/titan,thinkaurelius/titan,tomersagi/titan,mwpnava/titan,jamestyack/titan,wangbf/titan,samanalysis/titan,banjiewen/titan,ThiagoGarciaAlves/titan,kangkot/titan,graben1437/titan,hortonworks/titan,elubow/titan,xlcupid/titan,kalatestimine/titan,nvoron23/titan,anuragkh/titan,fengshao0907/titan,mbrukman/titan,kalatestimine/titan