add cache:pool:delete command

Author: Henry Snoek

components/cache/cache_pools.rst

@@ -127,9 +127,20 @@ when all items are successfully deleted)::
 .. tip::
 
     If the cache component is used inside a Symfony application, you can remove
-    *all items* from the *given pool(s)* using the following command (which resides within
+    items from cache pools using the following commands (which reside within
     the :ref:`framework bundle <framework-bundle-configuration>`):
 
+    To remove *one specific item* from the *given pool*:
+
+    .. code-block:: terminal
+
+        $ php bin/console cache:pool:delete <cache-pool-name> <cache-key-name>
+
+        # deletes the "cache_key" item from the "cache.app" pool
+        $ php bin/console cache:pool:delete cache.app cache_key
+
+    You can also remove *all items* from the *given pool(s)*:
+
     .. code-block:: terminal
 
         $ php bin/console cache:pool:clear <cache-pool-name>
@@ -140,6 +151,9 @@ when all items are successfully deleted)::
         # clears the "cache.validation" and "cache.app" pool
         $ php bin/console cache:pool:clear cache.validation cache.app
 
+.. versionadded:: 4.1
+    The ``cache:pool:delete`` command was introduced in Symfony 4.1.
+
 .. _component-cache-cache-pool-prune:
 
 Pruning Cache Items