Provide an example in the quick start section of README.md

[chrisimcevoy]

Nodatime provides a helpful example on its home page:

// Instant represents time from epoch
Instant now = SystemClock.Instance.GetCurrentInstant();

// Convert an instant to a ZonedDateTime
ZonedDateTime nowInIsoUtc = now.InUtc();

// Create a duration
Duration duration = Duration.FromMinutes(3);

// Add it to our ZonedDateTime
ZonedDateTime thenInIsoUtc = nowInIsoUtc + duration;

// Time zone support (multiple providers)
var london = DateTimeZoneProviders.Tzdb["Europe/London"];

// Time zone conversions
var localDate = new LocalDateTime(2012, 3, 27, 0, 45, 00);
var before = london.AtStrictly(localDate);

It would be nice to have a Pyoda version of this and include it in the README.md "quick start", which currently says "coming soon".

However:

>>> from pyoda_time import *
>>> now: Instant = SystemClock.instance.get_current_instant()
>>> now_in_iso_utc: ZonedDateTime = now.in_utc()
>>> duration: Duration = Duration.from_minutes(3)
>>> then_in_iso_utc: ZonedDateTime = now_in_iso_utc + duration
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for +: 'ZonedDateTime' and 'Duration'