Update configuration.md

Update configuration docs to match current code implementation.

docs/configuration.md

@@ -19,7 +19,7 @@ In order to use it, you must:
 
 ### Configuration initialisation
 
-The `Lcobucci\JWT\Signer\Key` object is used for symmetric/asymmetric signature.
+The `Lcobucci\JWT\Signer\Key\InMemory` object is used for symmetric/asymmetric signature.
 
 To initialise it, you can pass the key content as a plain text:
 
@@ -81,9 +81,11 @@ use Lcobucci\JWT\Signer;
 use Lcobucci\JWT\Signer\Key\LocalFileReference;
 use Lcobucci\JWT\Signer\Key\InMemory;
 
+// You may use RSA OR ECDSA and all their variations (256, 384, and 512) and EdDSA over Curve25519
+$signer        = new Signer\Rsa\Sha512();
+$signer        = Signer\Ecdsa\Sha512::create();
 $configuration = Configuration::forAsymmetricSigner(
-    // You may use RSA or ECDSA and all their variations (256, 384, and 512) and EdDSA over Curve25519
-    new Signer\Rsa\Sha256(),
+    $signer,
     LocalFileReference::file(__DIR__ . '/my-private-key.pem'),
     InMemory::base64Encoded('mBC5v1sOKVvbdEitdSBenu59nfNfhwkedkJVNabosTw=')
     // You may also override the JOSE encoder/decoder if needed by providing extra arguments here