add an official binary on every release

[sirdarckcat]

when creating a new release:

https://github.com/google/nsjail/releases/new

could you add an official binary?

alternatively, could you have an official Docker image with the every release?

https://github.com/google/nsjail/packages

this would allow users to not have to recompile from source every time

[robertswiecki]

Ok, let's sink about it :)

CC @happyCoder92

[happyCoder92]

Thanks for the PR 👍