Add missing steps for adding own types based on official Doctrine doc…

…umentation (martin-georgiev#47)

docs/INTEGRATING-WITH-DOCTRINE.md

@@ -1,4 +1,4 @@
-## Integration with Symfony
+## Integration with Doctrine
 
 
 *Register the DBAL types you plan to use*
@@ -21,6 +21,7 @@ Type::addType('text[]', "MartinGeorgiev\\Doctrine\\DBAL\\Types\\TextArray");
 
 *Register the functions you'll use in your DQL queries*
 
+
 Full set of the available types can be found [here](AVAILABLE-FUNCTIONS-AND-OPERATORS.md).
 
 ```php
@@ -33,7 +34,21 @@ $configuration = new Configuration();
 $configuration->addCustomStringFunction('TO_TSQUERY', MartinGeorgiev\Doctrine\ORM\Query\AST\Functions\ToTsquery::class);
 $configuration->addCustomStringFunction('TO_TSVECTOR', MartinGeorgiev\Doctrine\ORM\Query\AST\Functions\ToTsvector::class);
 $configuration->addCustomStringFunction('TSMATCH', MartinGeorgiev\Doctrine\ORM\Query\AST\Functions\Tsmatch::class);
-
 ...
+
 $em = EntityManager::create($dbParams, $configuration);
-```
+```
+
+*Then you need to register type mappings like below, based on [documentation](https://www.doctrine-project.org/projects/doctrine-orm/en/2.6/cookbook/custom-mapping-types.html)*
+
+```php
+$platform = $em->getConnection()->getDatabasePlatform();
+$platform->registerDoctrineTypeMapping('integer[]','integer[]');
+$platform->registerDoctrineTypeMapping('_int4','integer[]');
+$platform->registerDoctrineTypeMapping('bigint[]','bigint[]');
+$platform->registerDoctrineTypeMapping('_int8','bigint[]');
+$platform->registerDoctrineTypeMapping('text[]','text[]');
+$platform->registerDoctrineTypeMapping('_text','text[]');
+...
+
+```