Upgrade Guide v.5+ missing?

Dear community,

I want to upgrade my Laravel Mix to version 5.0.1 (as this is the default which comes with Laravel 6.x). I have upgraded my old version (1.0.7) to 4.0.0 without any problems. But after pulling in version 5.0.1 I start to receive a couple of errors regarding font imports in SASS. For every version there is a nice upgrade guide with breaking changes, but this seems to lack for version 5.0:

https://laravel-mix.com/docs/4.0/upgrade & https://laravel-mix.com/docs/4.1/upgrade are both the same.

Is there somewhere at least a list which tells me what breaking changes there are from 4.0 to 5.0 ?

Kind Regards