docs: clarify machine vs process tracking modes (#484)

[KReyes-py]

Description

Updated the methodology.md file to include a dedicated section for Tracking Modes. It clearly defines the differences between Machine Mode and Process Mode, explaining their scope and typical use cases.

Related Issue

#484 Closes #484

Motivation and Context

The current documentation was a bit unclear for new users regarding how CodeCarbon attributes power consumption. This change solves the confusion mentioned in issue #484 by providing a structured comparison, helping users choose the most accurate mode for their specific environment (dedicated hardware vs. shared clusters).

How Has This Been Tested?

I have verified the Markdown rendering in VS Code to ensure the formatting and links are correct. This is a documentation-only change.

Screenshots (if appropriate):

Types of changes

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• [x ] Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

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Checklist:

Go over all the following points, and put an x in all the boxes that apply.

• My code follows the code style of this project.
• [x ] My change requires a change to the documentation.
• [x ] I have updated the documentation accordingly.
• I have read the docs/how-to/contributing.md document.
• I have added tests to cover my changes.
• All new and existing tests passed.

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