formatInTimeZone link in readme is incorrect

[fgblomqvist]

It links to the old name:
https://github.com/marnusw/date-fns-tz#formataszonedtime

Rather than the new one:
https://github.com/marnusw/date-fns-tz#formatintimezone

Thanks for adding that function, it's exactly what this lib needed 😄

[marnusw]

Thank you for pointing that out.