examples: Add an example of resolving a known service by service name
examples: Add an example of resolving a known service by service name

To use:
* `avahi-publish-service -s 'My Service Name' _test._tcp 0`
* `./examples/resolver.py` should print a `ServiceInfo`
* Kill the `avahi-publish-service` process
* `./examples/resolver.py` should print `None`

Signed-off-by: Simon McVittie <0e1aea601907c1a85c2dc96e5ea37e23c58d2e9b@collabora.com>

jstasiak/python-zeroconf