Update PasswordEncoder declaration

Closes gh-10910

Author: talerngpong

docs/manual/src/docs/asciidoc/_includes/servlet/crypto/index.adoc

@@ -198,10 +198,13 @@ The password package of the spring-security-crypto module provides support for e
 [source,java]
 ----
 public interface PasswordEncoder {
+	String encode(CharSequence rawPassword);
 
-String encode(String rawPassword);
+	boolean matches(CharSequence rawPassword, String encodedPassword);
 
-boolean matches(String rawPassword, String encodedPassword);
+	default boolean upgradeEncoding(String encodedPassword) {
+		return false;
+	}
 }
 ----