Document DESCRIPTION fields that are checked

[seth127]

There are a number of metrics, (almost?) all of which we inherit from riskmetric, which rely on parsing specific fields in the DESCRIPTION file. Some examples:

• Has Website
• Has Version Control
• Has Bug Reports URL

I think we should document these somewhere, specifically so that a package maintainer who see a low score in these categories can easily know where they need to update to improve their score.

The best case scenario would be to document that we inherit these from riskmetric (do we already document this somewhere? I didn't see it) and point to their documentation about which DESCRIPTION fields are relevant. That way, our docs wouldn't risk getting out of date if they change how they parse this. However, I couldn't find any documentation on their end about this either. For example, neither this or this tells the user where it looks for a website URL.

I'm open to discussion on how best to approach this. To restate: my primary goal is to make it easy for package maintainers to know how to improve their score.

[seth127]

For the time being, an example of the most common simple fixes is in metrumresearchgroup/pmparams#2 (specifically this commit)