Allow `ignore-from-file` and `ignore` keys

[cdwilson]

I'm currently using a .yamlignore file to ignore a couple files in addition to the files ignored from .gitignore.

ignore-from-file:
  - .gitignore
  - .yamlignore

While this works, I'd really like to avoid having a separate file and just include these extra ignores as a list under the ignore key in my .yamllint file.

ignore-from-file: .gitignore

ignore:
  - .clang-format
  - pm_static.yml

The documentation mentions that ignore-from-file is mutually exclusive with the ignore key, but I didn't see any explanation of why. Would it be possible to change the behavior to allow both of these keys to be specified simultaneously?

[adrienverge]

Hello Chris,

Since ignore-from-file: accepts multiple files, I agree it could make sense if the contents of ignore: was interpreted as a last ignore file 👍

I'm not opposed to changing the behavior. However it might not be very easy: it would complexify the logic of parsing configuration (which is a bit touchy) + its tests, and for info this logic is already being updated currently (in #701).