Fixes#9219
@JunTaoLuo Dan calls out the implicit versioning "for 2.1 SDK or later;" however, we don't usually version the doc content by SDK release. We might need to say something for this update in the passage that I'm adding to the All topic (*aspnetcore/fundamentals/metapackage.md*) about which SDK version this applies to. I don't know if that's something that you would like to do or what version to call out.
I also remove the version from the samples. We also assume that devs are using the latest SDK with our samples.
* Add ASP.NET Core 2 features to Identity Configuration.
Fixed typo with ASP.NET Core 1 Cookie Name.
* Make things more clear and call out the specific options.
* Fix wording, spacing, typo on folder name. Display 1.x snippets with more context
* Fix typo
* Move properties and call out ASP.NET Core 1.x ones.
* Changes to split out the ASP.NET Core 2 Identity cofig from ASP.NET Core 1.
* Fix problem with number rendering
Show differences between ASP.NET Core 1.x and 2.x config.
* Fix extra spaces
Add snippet_ prefix to regions
* Correct what UseAuthentication does.
* Update snippet regions with snippet_ prefix.
* Updating to latest, cleaning up article and screenshots
* Update of Identity (#3653)
* WIP: Update of Identity
* Update identity.md
* Adding red box; adding link to account confirmation.