documentation on copyright headers?

[Wilko Meyer]

Hi Guix,

The "The Perfect Set-Up" chapter of guixes manual describes how to set
up copyright.el to support the process of inserting/updating ones
copyright header; however it doesn't answer:

- why a copyright header has to be inserted
- if a copyright header has to be inserted for all files that are
  subject to changes (is there a treshold? can it be left out for minor
  changes to files etc.?) of a sent patch.

I'm not too knowledgable in copyright law to answer these things myself
and would guess, that explaining this briefly could be useful in guixes
documentation on contributions.

-- 
Kind regards,

Wilko Meyer
w@wmeyer.eu