Update README.md

[brandonroth]

Fix compiler error by making API Parameter Abstraction example match CRUD & Authorization example.

[mattt]

Thanks for the PR, @brandonroth. Doing a quick search through the README showed a few other cases where an NSURL initializer needed to be updated (d7f07d1). One other stylistic difference is that I prefer to have the ! on the initializer itself, rather than add it on each use.