Update README

Author: Michaël Perrin

README.md

@@ -3,6 +3,7 @@ Docker configuration to run a Symfony app.
 ## Run
 
     docker-compose up -d
+    docker-compose exec php composer install
 
 You can now visit http://localhost and see the default Symfony page.
 
@@ -15,16 +16,43 @@ Symfony commands:
 
 ## Included stuff
 
+### Nginx
+
+The official Nginx image is used with a slight addition for permissions.
+
+The virtual host is defined in the [app.conf](docker/nginx/app.conf) file. This file is shared with the container
+as defined in the `docker-compose.yml` file. I prefer to share the host like this instead of using `COPY` in the Dockerfile
+as there is no need to build a new image if the host changes. A simple `docker-compose up -d` will take
+the new host into account.
+
+### PHP-FPM
+
+PHP-FPM 7.0 is installed with the following configuration:
+
+* Necessary extensions for Symfony
+* MySQL
+* GD
+* Composer
+* PHPUnit
+* Xdebug
+
+
 ### Xdebug
 
 Making Xdebug working with Docker is quite tricky as there is currently a limitation to Docker for Mac
 that prevents a container to make a request to the the host, which is exactly what we would like to do with Xdebug.
 
-To make Xdebug debugging work, you will first need to run this command:
+To make Xdebug debugging work, you will first need to run this command on the host:
 
     sudo ifconfig lo0 alias 10.200.10.1/24
 
-This IP address is configured in the environment variables of the PHP container (see `docker-compose.yml` file).
+This IP address is configured in the environment variables of the PHP container, in the `docker-compose.yml` file:
+
+    services:
+      php:
+        # ...
+        environment:
+          XDEBUG_REMOTE_HOST: 10.200.10.1
 
 No extra configuration is needed in your IDE (tested on Sublime Text, Visual Studio Code and Atom), apart the usual.