clarify settings
// - codes is an array which can contain error codes provided by a linter.
// - icon can be:
// one of the default icons: "circle", "dot" or "bookmark"
- // or a path to an icon file like (e.g. "Packages/icons/warning.png")
// or "none" to remove the icon
+ // or a path to an icon file like
+ // "Packages/SublimeLinter/gutter-themes/Blueberry Cross/error.png"
// or one provided by a gutter theme (e.g. "warning" or "error")
// in theme Default: "warning", "error", "cog", "x",
// and "diamond", "heart", "pointer", "square", "star", "triangle" all
