Fix code example in README

[aburkhalter512]

Fixes the code example in the README. The root of the problem was that the instance of the integer doesn't implement DependencyClone so replacing it with a reference fixes the problem. I additionally wrapped it in a struct to better represent actual usage (I don't expect raw integers to be added as instances as standard practice. Wrapping them in a "config" struct seems more likely)

Fixes https://github.com/p0lunin/teloc/issues/28