minor #12384 [OptionsResolver] Documented BC break (webmozart)

This PR was merged into the 2.6-dev branch.

Discussion
----------

[OptionsResolver] Documented BC break

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #12378
| License       | MIT
| Doc PR        | -

Commits
-------

0b0bfc0 [OptionsResolver] Documented BC break

UPGRADE-2.6.md

@@ -309,3 +309,43 @@ OptionsResolver
    $options = $resolver->resolve($options);
    ```
    
+ * When undefined options are passed, `resolve()` now throws an
+   `UndefinedOptionsException` instead of an `InvalidOptionsException`.
+   `InvalidOptionsException` is only thrown when option values fail their
+   validation constraints.
+   
+   Before:
+   
+   ```php
+   $resolver->setDefaults(array(
+       'transport' => 'smtp',
+       'port' => 25,
+   ));
+   $resolver->setAllowedTypes(array(
+       'port' => 'integer',
+   ));
+   
+   // throws InvalidOptionsException
+   $resolver->resolve(array('foo' => 'bar'));
+   
+   // throws InvalidOptionsException
+   $resolver->resolve(array('port' => '25'));
+   ```
+   
+   After:
+   
+   ```php
+   $resolver->setDefaults(array(
+       'transport' => 'smtp',
+       'port' => 25,
+   ));
+   $resolver->setAllowedTypes(array(
+       'port' => 'integer',
+   ));
+   
+   // throws UndefinedOptionsException
+   $resolver->resolve(array('foo' => 'bar'));
+   
+   // throws InvalidOptionsException
+   $resolver->resolve(array('port' => '25'));
+   ```

src/Symfony/Component/OptionsResolver/CHANGELOG.md

@@ -42,3 +42,5 @@ CHANGELOG
    RuntimeException
  * [BC BREAK] normalizers are not executed anymore for unset options
  * normalizers are executed after validating the options now
+ * [BC BREAK] an UndefinedOptionsException is now thrown instead of an
+   InvalidOptionsException when non-existing options are passed