[2.8] update readme files for new components

Author: xabbuh

src/Symfony/Component/Ldap/README.md

@@ -18,10 +18,7 @@ The documentation for the component can be found [online] [0].
 Resources
 ---------
 
-You can run the unit tests with the following command:
-
-    $ cd path/to/Symfony/Component/Ldap/
-    $ composer install
-    $ phpunit
-
-[0]: https://symfony.com/doc/2.8/components/ldap.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)

src/Symfony/Component/PropertyInfo/README.md

@@ -7,8 +7,7 @@ of popular sources.
 Resources
 ---------
 
-You can run the unit tests with the following command:
-
-    $ cd path/to/Symfony/Component/PropertyInfo/
-    $ composer install
-    $ phpunit
+  * [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)