Update Requests documentation to indicate this works in .NET too

[jamescrosswell]

@jamescrosswell do we support this now? If so, could you amend the docs? Docs still only say JS and Python: https://docs.sentry.io/product/insights/requests/#prerequisites-and-limitations

cc @smeubank (other SDKs also covered? might need docs changes)

Originally posted by @bruno-garcia in #3334