Merge branch '2.8' into 3.0

* 2.8:
  Updated all the README files
  [TwigBundle] Fix failing test on appveyor
  Improved the error message when using "@" in a decorated service
  Improve error reporting in router panel of web profiler
  [DoctrineBridge][Form] Fix performance regression in EntityType
  [FrameworkBundle] Fix a regression in handling absolute and namespaced template paths
  Allow to normalize \Traversable
  minor [Form] fix tests added by #16886
  Remove _path from query parameters when fragment is a subrequest and request attributes are already set Added tests for _path removal in FragmentListener
  Simplified everything
  Added a test
  Fixed the problem in an easier way
  Fixed a syntax issue
  Improved the error message when a template is not found
  [CodingStandards] Conformed to coding standards
  [TwigBundle] fixed Include file locations in "Template could not be found" exception

Author: fabpot

README.md

@@ -1,20 +1,15 @@
 OptionsResolver Component
 =========================
 
-This component processes and validates option arrays.
-
-Documentation
--------------
-
-The documentation for the component can be found [online] [1].
+The OptionsResolver component is `array_replace on steroids. It allows you to
+create an options system with required options, defaults, validation (type,
+value), normalization and more.
 
 Resources
 ---------
 
-You can run the unit tests with the following command:
-
-    $ cd path/to/Symfony/Component/OptionsResolver/
-    $ composer install
-    $ phpunit
-
-[1]: https://symfony.com/doc/current/components/options_resolver.html
+  * [Documentation](https://symfony.com/doc/current/components/options_resolver.html)
+  * [Contributing](https://symfony.com/doc/current/contributing/index.html)
+  * [Report issues](https://github.com/symfony/symfony/issues) and
+    [send Pull Requests](https://github.com/symfony/symfony/pulls)
+    in the [main Symfony repository](https://github.com/symfony/symfony)