Document how to access methods within specific model classes

Is your feature request related to a problem? Please describe.

CO2.js v0.16 introduced the ability to access methods that were previously private within a given model class. This was applied in PR https://github.com/thegreenwebfoundation/co2.js/pull/220.

These methods could be used by developers to do more than just estimate carbon emissions - allowing them to expose information about estimated energy use, operational v. embodied emissions, and more.

However, there's no documentation for these methods.

Describe the solution you'd like

These private methods should be documented on the Methods page in the CO2.js section of the docs website.

The methods to be document are:

Sustainable Web Design v4

• operationalEnergyPerSegment
• operationalEmissions
• embodiedEnergyPerSegment
• embodiedEmissions
• ratingScale

Sustainable Web Design v3

• energyPerByteByComponent
• co2byComponent
• energyPerByte
• energyPerVisitByComponent
• energyPerVisit
• emissionsPerVisitInGrams
• annualEnergyInKwh
• annualEmissionsInGrams
• annualSegmentEnergy
• ratingScale

Describe alternatives you've considered
We've tried to expose these via alternate tooling like JSR, however that's no possible without a rewrite of the library to TypeScript which is something we're not in a position to steward at this time.

Start with the Methods page in the CO2.js section and compare it with the referenced implementations in src/sustainable-web-design-v3.js and src/sustainable-web-design-v4.js. Document all listed methods, including their available inputs and outputs, so developers can use them to access energy, emissions, and rating information.