Rename auth.token.rootCertBundle yml field

Renames auth.token.rootCertBundle field in registry config to rootcertbundle so
that the REGISTRY_AUTH_TOKEN_ROOTCERTBUNDLE environment variable will override it.

See
()[https://github.com/docker/distribution/blob/master/configuration/parser.go#L155]

Signed-off-by: Donald Huang <don.hcd@gmail.com>

registry/auth/token/accesscontroller.go

@@ -146,7 +146,7 @@ type tokenAccessOptions struct {
 func checkOptions(options map[string]interface{}) (tokenAccessOptions, error) {
 	var opts tokenAccessOptions
 
-	keys := []string{"realm", "issuer", "service", "rootCertBundle"}
+	keys := []string{"realm", "issuer", "service", "rootcertbundle"}
 	vals := make([]string, 0, len(keys))
 	for _, key := range keys {
 		val, ok := options[key].(string)

registry/auth/token/token_test.go

@@ -261,7 +261,7 @@ func TestAccessController(t *testing.T) {
 		"realm":          realm,
 		"issuer":         issuer,
 		"service":        service,
-		"rootCertBundle": rootCertBundleFilename,
+		"rootcertbundle": rootCertBundleFilename,
 	}
 
 	accessController, err := newAccessController(options)