Merge pull request #177 from liip/phpcr-loader-doc

improve phpcr loader doc

Resources/doc/data-loader/doctrine-phpcr.md

@@ -10,12 +10,18 @@ service definition:
     <tag name="liip_imagine.data.loader" loader="doctrine_phpcr" />
     <argument type="service" id="liip_imagine" />
     <argument>%liip_imagine.formats%</argument>
-    <argument>%symfony_cmf_create.static_basepath%</argument>
+    <argument>%my_content_basepath%</argument>
     <argument type="service" id="doctrine_phpcr.odm.document_manager" />
     <argument>%symfony_cmf_create.image.model_class%</argument>
 </service>
 ```
 
+Instead of liip_imagine.formats you can of course also provide a custom set of
+image formats to support.
+``my_content_basepath`` is used to limit what parts of your repository are
+exposed by imagine. This must be a path without trailing slash. For example
+``"/cms/content`` or if you want to expose everything, ``""`` (but *not* ``"/"``).
+
 Note there is an AbstractDoctrineLoader. It is quite easy to extend this abstract class
 to create a new Doctrine loader for the ORM or another ODM.