Update README.rst

[strunker]

So I had some pretty big blockers using the new library and discovery methods. I also finally realized what kind of firewall rules need to be created in order for zeroconf discovery to work properly. On windows I created two rules. one inbound, one outbound, for ports 1900,5353 and allowed them through the firewall. Afterwards I was able to do proper chromecast discovery without needing to disable my firewall. I also added some additional examples on how to discover numerous devices by friendly name, and I think a super important thing to include is the param discovery_timeout. I was getting many more devices using get_chromecasts() that I was not getting with get_listed_chromecasts() so I examined the difference and realized the timing is much more aggressive by default on get_listed_chromecasts(), the param helps alleviate that, and accounts for networks\devices that are slower to respond.

[strunker]

Anyone out there who can review this? This really should be merged in the readme document doesnt really provide everything you need to know to be successful in setting things up.

[emontnemery]

pychromecast does not rely on SSDP for discovery, so we don't need to mention that. If you don't agree @strunker, please open another PR which motivates why SSDP is required.

[emontnemery]

Thanks @strunker 👍

I'm sorry about the very long delay for reviewing this.

[strunker]

Thanks @emontnemery all good on the delay. Hope these additions help others who run on Windows.