OP-151 - adds update explaining usage of fixtures in more details

Author: MacBalc

doc/fixtures.md

@@ -6,6 +6,7 @@ some necessary data in YAML file, which you can load to your database.
 If you are not familiar with the Sylius fixtures concept yet, please 
 read [this documentation page](http://docs.sylius.com/en/1.2/book/architecture/fixtures.html).
 
+
 ## General usage
 
-Just take a look at [this](../tests/Application/config/packages/bitbag_sylius_cms_plugin.yml) file.
+As you can see in [here](../tests/Application/config/packages/bitbag_sylius_cms_plugin.yml), cms fixtures are configured to be run under `default` suite. It means that after installing plugin all you need to do is run `bin/console sylius:fixtures:load` and all of cms fixtures will load as well.