Fixed documentation by removing duplicate document.
Fixed documentation by removing duplicate document.

Removed docs/mesos-documentation-guide.md which got replaced by
docs/documentation-guide.md.

Review: https://reviews.apache.org/r/41463/

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