Remove & from Command::args calls in documentation
Remove & from Command::args calls in documentation

Now that arrays implement `IntoIterator`, using
`&` is no longer necessary. This makes examples
easier to understand.

graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust