Add Keycloak to README

Was missed from #543.

Author: martincostello

README.md

@@ -144,6 +144,7 @@ If a provider you're looking for does not exist, consider making a PR to add one
 | Imgur | [![NuGet](https://buildstats.info/nuget/AspNet.Security.OAuth.Imgur?includePreReleases=false)](https://www.nuget.org/packages/AspNet.Security.OAuth.Imgur/ "Download AspNet.Security.OAuth.Imgur from NuGet.org") | [![MyGet](https://buildstats.info/myget/aspnet-contrib/AspNet.Security.OAuth.Imgur?includePreReleases=true)](https://www.myget.org/feed/aspnet-contrib/package/nuget/AspNet.Security.OAuth.Imgur "Download AspNet.Security.OAuth.Imgur from MyGet.org") | [Documentation](https://apidocs.imgur.com/?version=latest#authorization-and-oauth "Imgur developer documentation") |
 | Instagram | [![NuGet](https://buildstats.info/nuget/AspNet.Security.OAuth.Instagram?includePreReleases=false)](https://www.nuget.org/packages/AspNet.Security.OAuth.Instagram/ "Download AspNet.Security.OAuth.Instagram from NuGet.org") | [![MyGet](https://buildstats.info/myget/aspnet-contrib/AspNet.Security.OAuth.Instagram?includePreReleases=true)](https://www.myget.org/feed/aspnet-contrib/package/nuget/AspNet.Security.OAuth.Instagram "Download AspNet.Security.OAuth.Instagram from MyGet.org") | [Documentation](https://www.instagram.com/developer/authentication/ "Instagram developer documentation") |
 | KakaoTalk | [![NuGet](https://buildstats.info/nuget/AspNet.Security.OAuth.KakaoTalk?includePreReleases=false)](https://www.nuget.org/packages/AspNet.Security.OAuth.KakaoTalk/ "Download AspNet.Security.OAuth.KakaoTalk from NuGet.org") | [![MyGet](https://buildstats.info/myget/aspnet-contrib/AspNet.Security.OAuth.KakaoTalk?includePreReleases=true)](https://www.myget.org/feed/aspnet-contrib/package/nuget/AspNet.Security.OAuth.KakaoTalk "Download AspNet.Security.OAuth.KakaoTalk from MyGet.org") | [Documentation](https://developers.kakao.com/docs/latest/en/kakaologin/common "KakaoTalk developer documentation") |
+| Keycloak | [![NuGet](https://buildstats.info/nuget/AspNet.Security.OAuth.Keycloak?includePreReleases=false)](https://www.nuget.org/packages/AspNet.Security.OAuth.Keycloak/ "Download AspNet.Security.OAuth.Keycloak from NuGet.org") | [![MyGet](https://buildstats.info/myget/aspnet-contrib/AspNet.Security.OAuth.Keycloak?includePreReleases=true)](https://www.myget.org/feed/aspnet-contrib/package/nuget/AspNet.Security.OAuth.Keycloak "Download AspNet.Security.OAuth.Keycloak from MyGet.org") | [Documentation](https://www.keycloak.org/documentation.html "Keycloak developer documentation") |
 | Kloudless | [![NuGet](https://buildstats.info/nuget/AspNet.Security.OAuth.Kloudless?includePreReleases=false)](https://www.nuget.org/packages/AspNet.Security.OAuth.Kloudless/ "Download AspNet.Security.OAuth.Kloudless from NuGet.org") | [![MyGet](https://buildstats.info/myget/aspnet-contrib/AspNet.Security.OAuth.Kloudless?includePreReleases=true)](https://www.myget.org/feed/aspnet-contrib/package/nuget/AspNet.Security.OAuth.Kloudless "Download AspNet.Security.OAuth.Kloudless from MyGet.org") | [Documentation](https://developers.kloudless.com/docs/v1/authentication "Kloudless developer documentation") |
 | Lichess | [![NuGet](https://buildstats.info/nuget/AspNet.Security.OAuth.Lichess?includePreReleases=false)](https://www.nuget.org/packages/AspNet.Security.OAuth.Lichess/ "Download AspNet.Security.OAuth.Lichess from NuGet.org") | [![MyGet](https://buildstats.info/myget/aspnet-contrib/AspNet.Security.OAuth.Lichess?includePreReleases=true)](https://www.myget.org/feed/aspnet-contrib/package/nuget/AspNet.Security.OAuth.Lichess "Download AspNet.Security.OAuth.Lichess from MyGet.org") | [Documentation](https://lichess.org/api#section/Authentication "Lichess developer documentation") |
 | Line | [![NuGet](https://buildstats.info/nuget/AspNet.Security.OAuth.Line?includePreReleases=false)](https://www.nuget.org/packages/AspNet.Security.OAuth.Line/ "Download AspNet.Security.OAuth.Line from NuGet.org") | [![MyGet](https://buildstats.info/myget/aspnet-contrib/AspNet.Security.OAuth.Line?includePreReleases=false)](https://www.myget.org/feed/aspnet-contrib/package/nuget/AspNet.Security.OAuth.Line "Download AspNet.Security.OAuth.Line from MyGet.org") | [Documentation](https://developers.line.biz/en/docs/line-login/integrate-line-login "Line developer documentation") |