Readme should include screenshot example

[ZevEisenberg]

Someone told me about this library, and they sent me a screenshot of some example usage, and it told a super compelling story. Classic "a picture is worth a thousand words" stuff. I think if the readme had a sample screenshot at the top, it would make the use of this repo a lot easier to understand.

[ZevEisenberg]

I found a bunch of examples in https://github.com/cashapp/AccessibilitySnapshot/tree/master/Example/SnapshotTests/__Snapshots__/SnapshotTestingTests that you could probably use as-is, or it might be clever to craft something a little more illustrative.

[NickEntin]

Thanks Zev, that's a great idea! Do you have one example in mind you think would stand out? What about using the example from the blog post announcing the framework?

[ZevEisenberg]

That's a good one! Although for some reason, I was thinking that side-by-side would be more compelling. Something like this, but maybe smaller and with a few more controls.

But I think the one in the blog post is better than nothing.

[NickEntin]

I updated the README to include the sample snapshot from the blog post for now. I'm going to be going some more work on the documentation, so if I come up with a better example as part of that I'll update the README again.

[ZevEisenberg]

It looks great!