Definitions for Information, Warning, and Error Severities

In the code comments for the RuleSeverity enum, a warning does not follow PowerShell's "recommended" guidelines and Errors do not conform to PowerShell's "required" guidelines. Information rules are "recommended by PowerShell best practice".

I just posted #466 and now that I am thinking about it, I am not sure what the specific criteria is that would differentiate Warnings from Errors. For my team, at my company, we cannot have any hard coded passwords in a script, so this would definitely be an Error. However, that might not be the case for everyone everywhere.

The definitions of Warning and Error severity should be clearly defined in the documentation. I have some ideas and opinions here, as I am sure everyone in the PS community does. Would it make sense to use https://github.com/PoshCode/PowerShellPracticeAndStyle as a starting point for best practices and guidelines?

I am also wondering if it would make sense to have the ability to override severity levels for built in rules.

Start with the RuleSeverity enum comments and compare their current wording with the PowerShellPracticeAndStyle guidance linked in the issue. Define and document criteria that distinguish Information, Warning, and Error severities, and clarify whether built-in severity overrides are in scope.