document disk/memory requirements for build

[getify]

I keep running into issues building defra on micro VMs (e.g., nanode on linode, with 1GB ram, 25GB storage, and debian linux 13).

For example, by default my /tmp is 484MB, and it runs out of space during the build. I "fixed" that by pointing GOTMPDIR at /root/tmp-go so it can use the majority of the storage allocated to my / partition.

But then I get OOM failures exhausting my VM's ram. So I set up a 4GB swapfile assuming that should be enough for the build, and I still got OOM failure. :(

Can we document an estimate of disk and memory requirements for building defra in a typical linux environment?