Fix readme so that the example compiles

[moxley]

Fixes up the example in the README.md to get it to compile.

The addition of parentheses and the whitespace changes are from Elixir formatter, automatically added by my editor. Let me know if you want those backed out.

[falood]

Thanks. I think it's good idea to move MyApp.Server at the beginning of the docs, but about the formatter, it's better to add import_deps: [:maru] to .formatter.exs, so that we don't need addition parentheses

[moxley]

Very good point. Now updated with the maru formatter settings.

[falood]

@moxley Thanks@