add more documentation to distributedBuilds and what can be done if buildmachines are not always up
add more documentation to distributedBuilds and what can be done if buildmachines are not always up

git-svn-id: 71c8032c709790ec749031c4215f8515ac00dc5a@21409 70bd8c7a-acb8-0310-9f0d-9cc1c95dcdbb

falsifian/personal_nixos,falsifian/personal_nixos,falsifian/personal_nixos,falsifian/personal_nixos,falsifian/personal_nixos