Updated all the README files

Author: javiereguiluz

README.md

@@ -1,47 +1,20 @@
 CssSelector Component
 =====================
 
-CssSelector converts CSS selectors to XPath expressions.
-
-The component only goal is to convert CSS selectors to their XPath
-equivalents:
-
-```php
-use Symfony\Component\CssSelector\CssSelector;
-
-print CssSelector::toXPath('div.item > h4 > a');
-```
-
-HTML and XML are different
---------------------------
-
-The `CssSelector` component comes with an `HTML` extension which is enabled by
-default. If you need to use this component with `XML` documents, you have to
-disable this `HTML` extension. That's because, `HTML` tag & attribute names
-are always lower-cased, but case-sensitive in `XML`:
-
-```php
-// disable `HTML` extension:
-CssSelector::disableHtmlExtension();
-
-// re-enable `HTML` extension:
-CssSelector::enableHtmlExtension();
-```
-
-When the `HTML` extension is enabled, tag names are lower-cased, attribute
-names are lower-cased, the following extra pseudo-classes are supported:
-`checked`, `link`, `disabled`, `enabled`, `selected`, `invalid`, `hover`,
-`visited`, and the `lang()` function is also added.
+The CssSelector component converts CSS selectors to XPath expressions.
 
 Resources
 ---------
 
+  * [Documentation](https://symfony.com/doc/current/components/css_selector.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)
+
+Credits
+-------
+
 This component is a port of the Python cssselect library
 [v0.7.1](https://github.com/SimonSapin/cssselect/releases/tag/v0.7.1),
 which is distributed under the BSD license.
-
-You can run the unit tests with the following command:
-
-    $ cd path/to/Symfony/Component/CssSelector/
-    $ composer install
-    $ phpunit