Fix platform-specific setup instructions

[ndporter]

The setup instructions include the following line:

If it’s not unzipped yet, double-click on it to unzip it. You should end up with a new folder called data.

Double-click to unzip is default behavior on Mac but not Windows (official Windows directions). I assume there's some variability on Linux. Directions should not be platform-specific for lessons designed for multiple platforms.

For consistency with the abbreviated nature of the remainder of the instructions, I suggest changing to:

If it’s not unzipped yet, unzip it. There should now be a folder called data in the r-novice-inflammation folder.

If the remainder of the instructions were more detailed, it might make sense to link to platform-specific instructions for true beginners there (that may not know how to unzip) but in that case, all three platforms would need to be represented.

[HaoZeke]

Excellent catch! Could you open a PR with the minimal instruction set? I'm reasonably certain handling three platforms for unzipping in this lesson is a bit overkill. Thanks and sorry for my late response