update README

README.md

@@ -1,43 +1,43 @@
 # ConsoleBundle
 
-Interact with Symfony's container through the command line. Uses [Psysh][psysh]
+Interact with Symfony's container through the command line. Uses [Psysh](http://psysh.org/)
 for the console.
 
 ## Installation
 
     composer require --dev mlo/console-bundle
 
 If you aren't using Symfony Flex, you will need to register the bundle in
-`app/AppKernel.php` in the `dev` and/or `test` environment.
+`AppKernel.php` in the `dev` and/or `test` environment.
 
-```
+```php
 if (in_array($this->getEnvironment(), array('dev', 'test'))) {
     $bundles[] = new Mlo\ConsoleBundle\MloConsoleBundle();
 }
 ```
 
+If you are using Symfony 4 or lower, require the [v1](https://github.com/mloberg/ConsoleBundle/tree/v1)
+version of this package.
+
+    composer require --dev mlo/console-bundle:^1.0
+
 ## Usage
 
-    bin/console console
-    # OR
     bin/console tinker
-    
+
 This will drop you in a Psysh shell with the variables `$container`, `$kernel`
-and `$this` which is mapped to the container.
+and `$this`, which references the container.
 
 ## Adding Variables
 
-If you have a service or parameter you access a lot, you can add them as a
-variable in the shell. In your `config_dev.yml` file add these lines:
+You can add custom variables to the shell scope with the following config:
 
 ```yaml
 mlo_console:
     variables:
-        debug: %kernel.debug%
+        debug: "%kernel.debug%"
         em: "@doctrine.orm.entity_manager"
 ```
 
 Now you will have a `$debug` variable with the value of the _kernel.debug_
 parameter and `$em` with your entity manager.
-
-[psysh]: http://psysh.org/