Added cross-links to relevant documentation

docs/en/reference/caching.rst

@@ -282,6 +282,8 @@ You can set the namespace a cache driver should use by using the
     <?php
     $cacheDriver->setNamespace('my_namespace_');
 
+.. _integrating-with-the-orm:
+
 Integrating with the ORM
 ------------------------
 

docs/en/reference/improving-performance.rst

@@ -26,6 +26,8 @@ Doctrine will need to load your mapping information on every single
 request and has to parse each DQL query on every single request.
 This is a waste of resources.
 
+See :ref:`integrating-with-the-orm`
+
 Alternative Query Result Formats
 --------------------------------
 
@@ -42,6 +44,8 @@ for updates, which means when you call flush on the EntityManager these entities
 even if properties changed. Read-Only allows to persist new entities of a kind and remove existing
 ones, they are just not considered for updates.
 
+See :ref:`annref_entity`
+
 Extra-Lazy Collections
 ----------------------
 
@@ -61,6 +65,7 @@ Apply Best Practices
 A lot of the points mentioned in the Best Practices chapter will
 also positively affect the performance of Doctrine.
 
+See :doc:`Best Practices <reference/best-practices>`
 
 Change Tracking policies
 ------------------------