Polish How-to Customize UserInfo response

Remove another extraneous numbered callout.

Issue gh-537

docs/src/docs/asciidoc/examples/src/main/java/sample/userinfo/EnableUserInfoSecurityConfig.java

@@ -144,7 +144,7 @@ public class EnableUserInfoSecurityConfig {
 		return new ImmutableJWKSet<>(jwkSet);
 	}
 
-	private static KeyPair generateRsaKey() { // <6>
+	private static KeyPair generateRsaKey() {
 		KeyPair keyPair;
 		try {
 			KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");