Update docs.microsoft.com links to learn.microsoft.com

[Youssef1313]

Similar to dotnet/roslyn#64268

The most important link to update is:

roslyn-analyzers/src/Utilities/Compiler/DiagnosticDescriptorHelper.cs

Line 36 in bce5d7e

var helpLink = $"https://docs.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/{id.ToLowerInvariant()}";

But consider updating all links (even code comments).