Elaborate on settings.ini usage and format

[kneitinger]

I use autorandr on a system that has a redshift daemon running to adjust the color temperature. I had found that every time I used autorandr, it would set the current gamma, then redshift would adjust based on that, magnifying the effect.

It took me quite some time to identify that the gamma option was at play, and then I had to look at the autorandr source to figure out the expected format of the settings.ini file.

This PR addresses both of those by clarifying the INI format (with an example) and illustrating an example scenario that mentions redshift so that users down the line will land somewhere if they Ctrl-f -> "redshift" on the README, which might prevent future "bug" reports :)

Thanks for all of your work!

[phillipberndt]

Thanks for your contribution and sorry for the long delay. I lost track of the PR queue. Merged.

[kneitinger]

No worries, we all know how that goes! Thanks for merging!