Add usage instructions

Fixes #1

README.md

@@ -8,4 +8,27 @@ An example of running Drupal 8.8 on Symfony’s [local web server][docs].
 
 ## Usage
 
-TODO
+1. Install the Symfony CLI from <https://symfony.com/download>.
+1. Clone this repository
+    ```bash
+    git clone https://github.com/opdavies/symfony-server-drupal-test.git
+
+    cd symfony-server-drupal-test
+    ```
+1. Run `composer install` to download all of the project’s dependencies (Drupal core, Examples module etc).
+1. Run `docker-compose up -d` to start the Docker container for MySQL. (You can run `docker-compose ps` afterwards to confirm that it’s running).
+1. Run `symfony server:start` to start the web server.
+1. Use Drush to install Drupal, prefixed by `symfony php` to allow access to the environment variables needed in `settings.php`:
+    ```bash
+    cd web
+
+    symfony php ../vendor/bin/drush site:install --no-interaction
+    ```
+1. Go to http://127.0.0.1:8000 to view the site.
+1. To run tests, PHPUnit also needs to be prefixed with `symfony php`:
+    ```bash
+    cd web
+
+    symfony php ../vendor/bin/phpunit -c core core/modules/action
+    ```
+1. Run `symfony server:stop` to stop the web server.