For linters that have fixers, make suggestions

[glasnt]

While still in beta, GitHub has "suggested changes"

https://help.github.com/articles/incorporating-feedback-in-your-pull-request/#applying-a-suggested-change

The format of which is a codeblock with the name 'sugguestion' ('```suggestion')

I'm not entirely sure if any of our current linters support autofixing, but for those that do, this might be useful.