[PsrHttpMessageBridge] Streamline README.md with other components

Author: derrabus

README.md

@@ -6,14 +6,8 @@ Provides integration for PSR7.
 Resources
 ---------
 
-  * [Documentation](https://symfony.com/doc/current/components/psr7.html)
-
-Running the tests
------------------
-
-If you want to run the unit tests, install dev dependencies before
-running PHPUnit:
-
-    $ cd path/to/Symfony/Bridge/PsrHttpMessage/
-    $ composer.phar install
-    $ phpunit
+ * [Documentation](https://symfony.com/doc/current/components/psr7.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)