Documentation: Remove defaulting to "John Does" as airframe maintainer

[MaEtUgR]

Solved Problem

When looking at airframe documentation @RomanBapst found that it's ridiculous to have "John Doe" as maintainer for many airframes. It's just a mock person and the information doesn't add any value but just clutter the documentation and possibly even cause confusion.

Solution

Remove the default string for the maintainer defined in the airframe parsing script. If no maintainer is defined then no maintainer should be added.

Changelog Entry

Documentation: Remove defaulting to "John Does" as airframe maintainer

Alternatives

We could also fail the parsing when no maintainer is defined but in my eyes that's too strict and gets into people's way.

Test coverage

It still parses and builds, we need to check that None actually causes the behavior we want or if it needs to be an empty string.

Context

[sfuhrer]

Agree with the functional change - the CI failures look rather real though, somewhere maintainer = None seems to cause issues.