note requirement on `wget` package

[jimkring]

It's worth noting that this action requires wget to be installed. I'm working with a container that doesn't already have it installed, so I had to install it. Not a big deal, but maybe work mentioning.

[rui314]

Alternatively, I could make a change to this Action so that it wouldn't try to install mold if wget is not available. Which do you prefer?

[jimkring]

I would probably prefer that mold detects the missing dependency and reports a descriptive message like "The 'wget' package is required to setup mold. Please ensure it's installed on your system (e.g. using your system's package manager) and then try again."

Thanks again for mold -- it's great!