[Onboarding] .NET fundamentals documentation

[meaghanlewis]

Describe the issue or suggestion

• Read through .NET fundamentals documentation
• Look for places where there might be gaps in information, or where information is unclear
• Understand whether there's a clear path to progress through fundamentals

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Associated WorkItem - 486864

[meaghanlewis]

I'm done with this initial exploration. I took notes and have some ideas of things that can be improved.

The next step is to share my notes and discuss with others who have ideas about what to improve in the .NET fundamentals.

I'll have a follow-up issue for October '25.