Adding more details about the steps in the readme for newcomers

In the readme, it is said:

Make sure that:
> Your builds are published to GitHub Releases
Your builds are code-signed

It would be useful to give more details about these.
Speaking as a newcomer to this kind of release flow.

* "Github releases": do we need to attach / add the binaries to each drafted release? Or is the code somehow pulled, built and magically hosted?

* "code-signed": how can one do this properly? some link and/or details?
For example, electron-builder has [this doc](https://www.electron.build/code-signing)