Include examples of "out of the box" logs format in the README

[Kerruba]

Currently, in the README is possible to see an example of a colorized pretty-printed output.
This is very cool, although it would be useful for someone stumbling upon this library knowing what's the default behavior without any of the configured parameters.

Sometimes it's useful to print everything on a single line and let the use possibly format the output, and some people would look for that specific feature first

Good stuff! 👍