Added empty line for list in maintenance doc.
Added empty line for list in maintenance doc.

Review: https://reviews.apache.org/r/44433/

abudnik/mesos,neilconway/mesos,neilconway/mesos,chhsia0/mesos,Gilbert88/mesos,yuquanshan/customizedMesos,kaysoky/mesos,Gilbert88/mesos,neilconway/mesos,verizonlabs/mesos,jpeach/mesos,abudnik/mesos,Aman-Jain-14/customizedMesos,zmalik/mesos,reneploetz/mesos,abudnik/mesos,craimbert/mesos,asamerh4/mesos,verizonlabs/mesos,chhsia0/mesos,asamerh4/mesos,jpeach/mesos,gsantovena/mesos,yuquanshan/customizedMesos,verizonlabs/mesos,gsantovena/mesos,yuquanshan/customizedMesos,asamerh4/mesos,gsantovena/mesos,verizonlabs/mesos,abudnik/mesos,chhsia0/mesos,neilconway/mesos,Aman-Jain-14/customizedMesos,andschwa/mesos,andschwa/mesos,zmalik/mesos,Gilbert88/mesos,kaysoky/mesos,jpeach/mesos,jpeach/mesos,yuquanshan/customizedMesos,Aman-Jain-14/customizedMesos,craimbert/mesos,chhsia0/mesos,yuquanshan/customizedMesos,kaysoky/mesos,andschwa/mesos,kaysoky/mesos,andschwa/mesos,Aman-Jain-14/customizedMesos,zmalik/mesos,kaysoky/mesos,craimbert/mesos,dforsyth/mesos,Aman-Jain-14/customizedMesos,jpeach/mesos,zmalik/mesos,asamerh4/mesos,reneploetz/mesos,craimbert/mesos,dforsyth/mesos,chhsia0/mesos,Gilbert88/mesos,abudnik/mesos,Aman-Jain-14/customizedMesos,asamerh4/mesos,andschwa/mesos,chhsia0/mesos,kaysoky/mesos,chhsia0/mesos,craimbert/mesos,Gilbert88/mesos,jpeach/mesos,reneploetz/mesos,reneploetz/mesos,verizonlabs/mesos,dforsyth/mesos,reneploetz/mesos,craimbert/mesos,dforsyth/mesos,gsantovena/mesos,abudnik/mesos,abudnik/mesos,verizonlabs/mesos,neilconway/mesos,gsantovena/mesos,kaysoky/mesos,andschwa/mesos,zmalik/mesos,craimbert/mesos,andschwa/mesos,reneploetz/mesos,gsantovena/mesos,gsantovena/mesos,asamerh4/mesos,neilconway/mesos,dforsyth/mesos,reneploetz/mesos,Gilbert88/mesos,zmalik/mesos,verizonlabs/mesos,Aman-Jain-14/customizedMesos,neilconway/mesos,dforsyth/mesos,zmalik/mesos,asamerh4/mesos,yuquanshan/customizedMesos,yuquanshan/customizedMesos,jpeach/mesos,dforsyth/mesos,Gilbert88/mesos