Updates links to Dex

Author: timhughes

content/en/docs/reference/access-authn-authz/authentication.md

@@ -328,7 +328,7 @@ tokens on behalf of another.
 Kubernetes does not provide an OpenID Connect Identity Provider.
 You can use an existing public OpenID Connect Identity Provider (such as Google, or
 [others](https://connect2id.com/products/nimbus-oauth-openid-connect-sdk/openid-connect-providers)).
-Or, you can run your own Identity Provider, such as CoreOS [dex](https://github.com/coreos/dex),
+Or, you can run your own Identity Provider, such as [dex](https://dexidp.io/),
 [Keycloak](https://github.com/keycloak/keycloak),
 CloudFoundry [UAA](https://github.com/cloudfoundry/uaa), or
 Tremolo Security's [OpenUnison](https://github.com/tremolosecurity/openunison).
@@ -339,13 +339,13 @@ For an identity provider to work with Kubernetes it must:
 2.  Run in TLS with non-obsolete ciphers
 3.  Have a CA signed certificate (even if the CA is not a commercial CA or is self signed)
 
-A note about requirement #3 above, requiring a CA signed certificate.  If you deploy your own identity provider (as opposed to one of the cloud providers like Google or Microsoft) you MUST have your identity provider's web server certificate signed by a certificate with the `CA` flag set to `TRUE`, even if it is self signed.  This is due to GoLang's TLS client implementation being very strict to the standards around certificate validation.  If you don't have a CA handy, you can use [this script](https://github.com/coreos/dex/blob/1ee5920c54f5926d6468d2607c728b71cfe98092/examples/k8s/gencert.sh) from the CoreOS team to create a simple CA and a signed certificate and key pair.
+A note about requirement #3 above, requiring a CA signed certificate.  If you deploy your own identity provider (as opposed to one of the cloud providers like Google or Microsoft) you MUST have your identity provider's web server certificate signed by a certificate with the `CA` flag set to `TRUE`, even if it is self signed.  This is due to GoLang's TLS client implementation being very strict to the standards around certificate validation.  If you don't have a CA handy, you can use [this script](https://github.com/dexidp/dex/blob/master/examples/k8s/gencert.sh) from the Dex team to create a simple CA and a signed certificate and key pair.
 Or you can use [this similar script](https://raw.githubusercontent.com/TremoloSecurity/openunison-qs-kubernetes/master/src/main/bash/makessl.sh) that generates SHA256 certs with a longer life and larger key size.
 
 Setup instructions for specific systems:
 
 - [UAA](https://docs.cloudfoundry.org/concepts/architecture/uaa.html)
-- [Dex](https://github.com/dexidp/dex/blob/master/Documentation/kubernetes.md)
+- [Dex](https://dexidp.io/docs/kubernetes/)
 - [OpenUnison](https://www.tremolosecurity.com/orchestra-k8s/)
 
 #### Using kubectl