A user correctly points out that some sentences were confusing, like:
It can also make reverse-engineering harder, as an end user could
guess what version of Go or garble you're using.
Rewrite the whole section. It now also explains what I meant by that
sentence with a practical example.
I also merged the bits about "provide your own seed" and "rotating the
seeds", because they're both talking about the same mechanism.
Fixes#666.