Docs fixes

Signed-off-by: alexmerlin <alex.merlin.1985@gmail.com>

Author: alexmerlin

docs/book/v3/configuration.md

@@ -2,6 +2,8 @@
 
 After installation, register `dot-navigation` in your project by adding the below line to your configuration aggregator (usually: `config/config.php`):
 
-     Dot\Navigation\ConfigProvider::class,
+```php
+Dot\Navigation\ConfigProvider::class,
+```
 
 Locate dot-navigation's distributable config file `vendor/dotkernel/dot-navigation/config/autoload/navigation.global.php.dist` and duplicate it in your project as `config/autoload/navigation.global.php`

docs/book/v3/installation.md

@@ -2,4 +2,6 @@
 
 Install `dotkernel/dot-navigation` by executing the following Composer command:
 
-    composer require dotkernel/dot-navigation
+```shell
+composer require dotkernel/dot-navigation
+```

docs/book/v4/configuration.md

@@ -2,6 +2,8 @@
 
 After installation, register `dot-navigation` in your project by adding the below line to your configuration aggregator (usually: `config/config.php`):
 
-     Dot\Navigation\ConfigProvider::class,
+```php
+Dot\Navigation\ConfigProvider::class,
+```
 
 Locate dot-navigation's distributable config file `vendor/dotkernel/dot-navigation/config/autoload/navigation.global.php.dist` and duplicate it in your project as `config/autoload/navigation.global.php`

docs/book/v4/installation.md

@@ -2,4 +2,6 @@
 
 Install `dotkernel/dot-navigation` by executing the following Composer command:
 
-    composer require dotkernel/dot-navigation
+```shell
+composer require dotkernel/dot-navigation
+```