Clearer when using a range expression

[gvwilson]

I had to read the c(...) very carefully to make sure it was just a range - I think that'll be more immediately clear this way.

[garrettgman]

@gvwilson I'm not in favor of the change because : is not explained in this tutorial (i.e. it falls into the expert blindspot). But it does raise the question, when should we consider a feature of the language to be basic knowledge? Also, when should we expect students to take tutorials in order? I can be convinced if you want to try.

[gvwilson]

We could avoid the problem by using c(1, 2, 3, 4, 5) (so that it's immediately obvious that it's a continuous range) - I think that splitting that into two's would illustrate the point well enough (?). Alternatively, the text could say, "We'll create the vector of numbers from 1 to 10 using the range notation 1:10" and then the code could show it - I don't think anyone reading this tutorial will be thrown by that at all.