Port two exceptions from System.Linq triple slash comments to Docs

[carlossanlop]

Summary

Found a couple of exceptions that were mentioned in the source code triple slash comments of System.Linq but were not yet in dotnet-api-docs. Seemed important since they describe two obsolete functions that should always throw when called.

Fixes #Issue_Number (if available)

[carlossanlop]

@mairaw @rpetrusha Please take a look whenever possible.

Adding the area owner @maryamariyan in case there are any additional comments or suggestions.

[rpetrusha]

Thanks for adding these exceptions, @carlossanlop. Could you remove the other documented exceptions for these two method overloads? This is evidently a copy and paste error; nothing other than a NotSupportedException can actually be thrown.