Added Installing and Configuring documentation.

Author: Aitor Brazaola

docs/first_use_installing_and_configuring.md

@@ -1,3 +1,48 @@
 # Installing and configuring
 
-> TODO
+The easiest way to install this bundle is using Composer
+```bash
+$ composer require lin3s/pattern-library-builder
+```
+Register the Bundle in your AppKernel 
+```php
+$bundles = [
+    ...
+    new Lin3sPatternLibraryBuilderBundle(),
+    ...
+];
+```
+Configure the basic settings in your `config.yml`:
+```yaml
+lin3s_pattern_library_builder:
+    theme:
+        title: "My title"
+        description: "My description"
+        custom_styles:
+            color_primary: "#000"
+        logo: ~
+    templates_config_files_path: "%kernel.root_dir%/PatternLibrary"
+```
+Add routes to access the Design System in your routing file:
+```yaml
+_pattern_library:
+    resource: "@Lin3sPatternLibraryBuilderBundle/Resources/config/routing.yml"
+```
+Create a folder in your AppBundle kernel root named `PatternLibrary` to store the Pattern Library configuration
+and create an index configuration file.
+```yaml
+status: 0
+description: '<p>This is the icon card component description.</p>'
+renderer:
+    type: homepage
+    options:
+        sections: []
+```
+Create a folder in your project's root named `templates` with the different subfolders of templates you want to have. 
+
+Install assets 
+```bash
+$ bin/console assets:install --symlink
+``` 
+
+Now you can navigate to `http://localhost:8000/design-system` and see the index page.