Doc gap: .NET 8 self-contained deployment default change not prominently documented

[GrantMeStrength]

Problem

A Stack Overflow question with 16k views describes a developer using dotnet publish --self-contained but the app still prompts for .NET installation: https://stackoverflow.com/questions/74281037/dotnet-publish-self-contained-running-the-app-still-asks-for-net-installat

The root cause is a .NET 8 breaking change: runtime-specific publishing no longer implies self-contained by default. Developers familiar with earlier .NET behavior are hit by this silently.

Suggested improvements

1. Add a callout near the self-contained docs explicitly calling out the .NET 8 default change
2. Add a troubleshooting section for 'it's asking for .NET even though I published --self-contained'
3. Add guidance on verifying publish output is truly self-contained

Reported as part of a Windows developer docs indie dev initiative (ADO #570454).