Comments fields on all models

[bluecmd]

Hi,

I would like to propose to add the Comments markdown field to all models, instead of the somewhat arbitrary list of models that have it today.

Another issue #4441 wanted to add the comments field to a few extra models and was de-duped against another bug that ended up not adding the comments field as far as I can tell from reading the related issue.

I am asking to add the comments field on all models as a general rule. There might be models that it makes no sense on that I am overlooking, but on the top of my head I cannot think of any.

Thoughts?

[bluecmd]

Ping @The-Only-God who might be interested in this.