Update contributing docs

[jjonescz]

Fixes #5996.

• Replaced references to razor-tooling with razor.
• Updated "Debugging with experimental Roslyn bits" to what actually worked for me.

[davidwengier]

Surely the microsoft.* pattern covers this

[jjonescz]

No, more specific patterns win: https://learn.microsoft.com/en-us/nuget/consume-packages/package-source-mapping#package-pattern-precedence

[davidwengier]

Right, but isn't it still redundant having both for the same package source?

[jjonescz]

I don't think so. I started with just microsoft.*, but then NuGet complained that Microsoft.CommonLanguageServerProtocol.Framework cannot be found, because it was trying to find it in different source. Adding that pattern is what worked for me.

[davidwengier]

Ahh, I see. That makes sense actually, because I just checked and there are other groups that are that specific, so if you want to override you'd have to be as specific. Thanks!