feature #14495 [Cache] Adds mention of using FileSystemTagAwareAdatpter (andrerom)

This PR was squashed before being merged into the 4.4 branch.

Discussion
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[Cache] Adds mention of using FileSystemTagAwareAdatpter

As mention of RedisTagAwareAdapter was added in 83fe3d7, this should potentially be enough to
fix #12446

Commits
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24312cb [Cache] Adds mention of using FileSystemTagAwareAdatpter

Author: OskarStark

components/cache/adapters/filesystem_adapter.rst

@@ -55,5 +55,18 @@ and cache root path as constructor parameters::
     :ref:`pruning of expired cache items <component-cache-cache-pool-prune>` by
     calling its ``prune()`` method.
 
+
+.. _filesystem-tag-aware-adapter:
+
+Working with Tags
+-----------------
+
+In order to use tag-based invalidation, you can wrap your adapter in :class:`Symfony\\Component\\Cache\\Adapter\\TagAwareAdapter`, but it's often more interesting to use the dedicated :class:`Symfony\\Component\\Cache\\Adapter\\FilesystemTagAwareAdapter`. Since tag invalidation logic is implemented using links on filesystem, this adapter offers better read performance when using tag-based invalidation::
+
+    use Symfony\Component\Cache\Adapter\FilesystemTagAwareAdapter;
+
+    $cache = new FilesystemTagAwareAdapter();
+
+
 .. _`tmpfs`: https://wiki.archlinux.org/index.php/tmpfs
 .. _`RAM disk solutions`: https://en.wikipedia.org/wiki/List_of_RAM_drive_software

components/cache/cache_invalidation.rst

@@ -61,7 +61,8 @@ method.
 .. note::
 
     When using a Redis backend, consider using :ref:`RedisTagAwareAdapter <redis-tag-aware-adapter>`
-    which is optimized for this purpose.
+    which is optimized for this purpose. When using File system, likewise consider to use
+    :ref:`FilesystemTagAwareAdapter <filesystem-tag-aware-adapter>`.
 
 The :class:`Symfony\\Component\\Cache\\Adapter\\TagAwareAdapter` class implements
 instantaneous invalidation (time complexity is ``O(N)`` where ``N`` is the number