Improve descriptions in configuration object

[fflaten]

The configuration object should probably provide better descriptions than xyz configuration. It currently shows this:

New-PesterConfiguration

Run          : Run configuration.
Filter       : Filter configuration
CodeCoverage : CodeCoverage configuration.
TestResult   : TestResult configuration.
Should       : Should configuration.
Debug        : Debug configuration for Pester. ⚠ Use at your own risk!
Output       : Output configuration
TestDrive    : TestDrive configuration.
TestRegistry : TestRegistry configuration.

This is a missed opportunity to ex. quickly mention how Filters work (exclude/include priority, union behavior etc) or as a minimum link to website for more details.

Inspiration:

It creates a union of two filters so all the tests specified in $configuration.Filter.FullName will be launched as well as all the tests having $configuration.Filter.Tag tags.

If that's the strategy we expect from Pester, maybe we could mention this behavior it in the New-PesterConfiguration Filter documentation.

Originally posted by @tempora-mutantur in #2278 (comment)

Related pester/docs#242

[fflaten]

Filter RFC: #1442