FAQ: Add dependency question

CC @moollaza 
This explanation doesn't feel right. It assumes too much context IMO. "Open the instant answer" -- That's incredibly vague.

Rather something like this:

Any Perl module (.pm file) that has external Perl dependencies will load them with a `use` statement. Typically these statements are located near the top of the file. For example, the Factors Goodie (lib/DDG/Goodie/Factors.pm) loads the class `Math::Prime::Util`. If this is not installed on your system DuckPAN will not be able to use the Factors Goodie and you will likely see an error or warning.

In order to install any missing dependencies you can use `cpan` or `cpanm` like so:

```bash
cpan install Math::Prime::Util
# or
cpanm Math::Prime::Util
```

Alternatively, if you would like to install **all** the dependencies for the repo (e.g. zeroclickinfo-goodies), you can run `duckpan installdeps`. Please note,  installing all the dependencies will take **several minutes** to install as there are many dependencies.