Documentation should be more specific about actions taken

[ggeldenhuis]

It is not 100% clear from the documentation whether the provider also actually runds grub2-mkconfig after setting/changing settings. It could be argued that it is obvious but for the sake of clarity it would be useful if the documentation could specifically say that grub2-mkconfig is run after setting a value. I looked through the code and that is indeed what happens. I am happy to do a tiny PR for the doc update if there is agreement.

[kenyon]

Looks like a duplicate of #40.

[raphink]

Thanks @kenyon