Updated upgrade documentation with changes in NetworkInfo protobuf.
Updated upgrade documentation with changes in NetworkInfo protobuf.

Review: https://reviews.apache.org/r/40238

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