Don't mention "*" dependency version in guessing game example
Don't mention "*" dependency version in guessing game example

It's a bad practice as far [RFC 1241] is concerned, and introducing it
in early tutorial may as well make it feel legitimate.

[RFC 1241]: https://github.com/rust-lang/rfcs/blob/master/text/1241-no-wildcard-deps.md
GBGamer/rust,GBGamer/rust,GBGamer/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,GBGamer/rust,GBGamer/rust,aidancully/rust,GBGamer/rust,graydon/rust,graydon/rust,GBGamer/rust,aidancully/rust,aidancully/rust,aidancully/rust,GBGamer/rust,aidancully/rust