Merge branch '5.0' into 5.1

* 5.0:
  Handle fetch mode deprecation of DBAL 2.11.
  Fixed handling of CSRF logout error
  [WebProfilerBundle] changed label of memory usage in time panel (Mb into MiB)
  [DotEnv][WebLink][Templating][ErrorHandler] Updated README with minimal example

Author: nicolas-grekas

README.md

@@ -4,10 +4,32 @@ Dotenv Component
 Symfony Dotenv parses `.env` files to make environment variables stored in them
 accessible via `$_SERVER` or `$_ENV`.
 
+Getting Started
+---------------
+
+```
+$ composer require symfony/dotenv
+```
+
+```php
+use Symfony\Component\Dotenv\Dotenv;
+
+$dotenv = new Dotenv();
+$dotenv->load(__DIR__.'/.env');
+
+// you can also load several files
+$dotenv->load(__DIR__.'/.env', __DIR__.'/.env.dev');
+
+// overwrites existing env variables
+$dotenv->overload(__DIR__.'/.env');
+
+// loads .env, .env.local, and .env.$APP_ENV.local or .env.$APP_ENV
+$dotenv->loadEnv(__DIR__.'/.env');
+```
+
 Resources
 ---------
 
-  * [Documentation](https://symfony.com/doc/current/components/dotenv.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)