Update README.md examples to reflect new version 0.18.0

Author: ponylang-main

README.md

@@ -10,7 +10,7 @@ hobby is beta quality software that will change frequently. Expect breaking chan
 
 * Requires ponyc 0.74.0 or later.
 * Install [corral](https://github.com/ponylang/corral)
-* `corral add github.com/ponylang/hobby.git --version 0.17.0`
+* `corral add github.com/ponylang/hobby.git --version 0.18.0`
 * `corral fetch` to fetch your dependencies
 * `use "hobby"` to include this package
 * `corral run -- ponyc` to compile your application