Either use sliding tag or latest tag in README.md

[phadej]

I copypasted the example, and it didn't work. This causes unnecessary confusion (#50).

[hazelweakly]

When I first wrote the README, I was under the impression that 1.1 would also be a sliding tag, but that turned out to not be the case. I agree that the readme should use v1 and I'm not sure why I didn't catch that sooner. I'll open a PR for that.