Update UG

Author: MGatner

user_guide_src/source/intro/psr.rst

@@ -27,11 +27,12 @@ CodeIgniter's :doc:`Logger </general/logging>` implements all of the interfaces
 This PSR provides a method for organizing file and namespaces to allow for a standard method of autoloading
 classes. Our :doc:`Autoloader </concepts/autoloader>` meets the PSR-4 recommendations.
 
-**PSR-6: Caching Interface**
+**PSR-6: Caching Interfaces**
+**PSR-16: SimpleCache Interface**
 
-CodeIgniter will not be trying to meet this PSR, as we believe it oversteps its needs. The newly proposed
-`SimpleCache Interfaces <https://github.com/dragoonis/fig-standards/blob/psr-simplecache/proposed/simplecache.md>`_
-do look like something we would consider.
+While the framework Cache components do not adhere to PSR-6 or PSR-16, a separate set of adapters are
+provided for both in ``CodeIgniter\Psr\Cache``. It is recommended that projects use the native Cache
+drivers directly as the adapters are only intended for compatibility with third-party libraries.
 
 **PSR-7: HTTP Message Interface**