Fix broken links

README.md

@@ -86,7 +86,7 @@ After parsing the file, it then determines the current context to use, the curre
 
 So our request has been sent, hooray! What next? This is where kube-apiserver enters the picture. As we've already mentioned, kube-server is the primary interface that clients and system components use to persist and retrieve cluster state. To perform its function, it needs to be able to verify that the requester is who they say there are. This process is called authentication.
 
-How does the apiserver authenticate requests? When the server first starts, it looks at all the [CLI flags](https://kubernetes.io/docs/admin/kube-apiserver/) the user provided and assembles a list of suitable authenticators. Let's take an example: if a `--client-ca-file` has been passed in, it appends the [x509 authenticator](); if it sees `--token-auth-file` provided, it appends the [token authenticator]() to the list. Every time a request is received, it is [run through the authenticator chain until one succeeds](): 
+How does the apiserver authenticate requests? When the server first starts, it looks at all the [CLI flags](https://kubernetes.io/docs/admin/kube-apiserver/) the user provided and assembles a list of suitable authenticators. Let's take an example: if a `--client-ca-file` has been passed in, it appends the x509 authenticator; if it sees `--token-auth-file` provided, it appends the token authenticator to the list. Every time a request is received, it is [run through the authenticator chain until one succeeds](https://github.com/kubernetes/apiserver/blob/51bebaffa01be9dc28195140da276c2f39a10cd4/pkg/authentication/request/union/union.go#L54): 
 
 - the [x509 handler](https://github.com/kubernetes/apiserver/blob/51bebaffa01be9dc28195140da276c2f39a10cd4/pkg/authentication/request/x509/x509.go#L60) will verify that the HTTP request is encoded with a TLS key signed by the CA root cert
 - the [bearer token handler](https://github.com/kubernetes/apiserver/blob/51bebaffa01be9dc28195140da276c2f39a10cd4/pkg/authentication/request/bearertoken/bearertoken.go#L38) will verify that the provided token (specified in the HTTP Authorization header) exists in the file on disk specified by `--token-auth-file`