Updated all the README files

Author: javiereguiluz

README.md

@@ -1,21 +1,13 @@
 Yaml Component
 ==============
 
-YAML implements most of the YAML 1.2 specification.
-
-```php
-use Symfony\Component\Yaml\Yaml;
-
-$array = Yaml::parse(file_get_contents(filename));
-
-print Yaml::dump($array);
-```
+The Yaml component loads and dumps YAML files.
 
 Resources
 ---------
 
-You can run the unit tests with the following command:
-
-    $ cd path/to/Symfony/Component/Yaml/
-    $ composer install
-    $ phpunit
+  * [Documentation](https://symfony.com/doc/current/components/yaml/index.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)