Update installation instructions to get new users started more easily

docs/eca/install.md

@@ -5,22 +5,18 @@ tags:
 ---
 # Installation
 
-To download the module with composer use the following command:
+ECA can use different modellers. The recommended BPMN.iO modeller is used in this Quick Start guide.
+
+Download the ECA module and BPMN.iO modeller module:
 
 ```
-composer require drupal/eca
+composer require drupal/eca drupal/bpmn_io
 ```
 
-??? note "Using non-stable releases"
-
-    If you want to use non-stable releases (e.g. RC, beta or dev), then you should configure your root project
-    to allow that by configuring the minimum acceptable stability with e.g. `composer config minimum-stability beta` for
-    accepting beta releases. Without this, composer may run into dependency issues.
-
-Enable the module(s) in the admin ui of your site (`/admin/modules`) or with drush:
+Enable these modules via the GUI at `/admin/modules` or with Drush:
 
 ```
-drush en eca eca_base eca_ui
+drush in eca eca_base eca_ui bpmn_io eca_modeller_bpmn
 ```
 
-The list of modules you may want to install depends on your use-case.
+The list of modules you may want to install depends on your use-case. You can now start building your own models.