Port System.Runtime.Intrinsics docs for .NET 9 APIs #105989
Description
NOTE: I still have to merge this PR. I just need to take care of the feedback, which is complex to address: dotnet/dotnet-api-docs#10155
Below is the list of APIs that still show up as undocumented in dotnet-api-docs and were introduced in .NET 9.
Full porting instructions can be found in the main issue.
This task needs to be finished the day before the RC2 snap (September 15th).
P7 Undoc APIs as of 08/20: #105989 (comment)