doc: serialization

Author: mle86

README.md

@@ -149,6 +149,11 @@ of external values without wrapping them in an instance.
 This extension of `AbstractValue` provides easy serializability for the Value objects.
 It implements the [JsonSerializable](https://php.net/manual/class.jsonserializable.php) interface.
 
+Standard PHP serialization via [serialize](https://secure.php.net/serialize)/[unserialize](https://secure.php.net/unserialize)
+is always supported.
+This class contains an extra `__wakeup()` implementation
+to make sure that unserialized instances always contain a valid value.
+
 * <code>public function <b>\_\_toString</b>(): string</code>
 
   Returns the wrapped value like `value()`, but with an explicit

src/AbstractSerializableValue.php

@@ -6,6 +6,10 @@
  * This extension of AbstractValue provides easy serializability
  * for the Value objects.  It implements the JsonSerializable interface.
  *
+ * Standard PHP serialization via {@see serialize}/{@see unserialize} is always supported.
+ * This class contains an extra {@see __wakeup} implementation
+ * to make sure that unserialized instances always contain a valid value.
+ *
  * @author Maximilian Eul
  * @link https://github.com/mle86/php-value
  */