[Proposal] [5.6] Rename stack log driver to prevent confusion with slack log driver

[SjorsO]

Laravel 5.6 introduces a reworked logging system. It looks great, it is definitely an improvement over the old system. The only problem i have with it is that the new stack driver is named very similarly to the new slack driver. I've already confused the two multiple times while reading trough the documentation and the logging config file.

I know its a minor problem, but i feel like its worth considering a name change before 5.6 releases.

[taylorotwell]

They are different words.