docs: add "Configuring Caching"

Author: kenjis

user_guide_src/source/general/caching.rst

@@ -30,6 +30,33 @@ browser.
 .. note:: The Benchmark tag is not cached so you can still view your page
     load speed when caching is enabled.
 
+Configuring Caching
+===================
+
+Setting Cache Engine
+--------------------
+
+Before using Web Page Caching, you must set the cache engine up by editing
+**app/Config/Cache.php**. See :ref:`libraries-caching-configuring-the-cache`
+for details.
+
+Setting $cacheQueryString
+-------------------------
+
+You can set whether or not to include the query string when generating the cache
+with ``Config\Cache::$cacheQueryString``.
+
+Valid options are:
+
+- ``false``: (default) Disabled. The query string is not taken into account; the
+  same cache is returned for requests with the same URI path but different query
+  strings.
+- ``true``: Enabled, take all query parameters into account. Be aware that this
+  may result in numerous cache generated for the same page over and over
+  again.
+- **array**: Enabled, but only take into account the specified list of query
+  parameters. E.g., ``['q', 'page']``.
+
 Enabling Caching
 ================
 
@@ -48,9 +75,6 @@ you. Once the tag is in place, your pages will begin being cached.
 .. important:: If you change configuration options that might affect
     your output, you have to manually delete your cache files.
 
-.. note:: Before the cache files can be written you must set the cache
-    engine up by editing **app/Config/Cache.php**.
-
 Deleting Caches
 ===============
 

user_guide_src/source/libraries/caching.rst

@@ -23,6 +23,8 @@ You can grab an instance of the cache engine directly through the Services class
 
 .. literalinclude:: caching/002.php
 
+.. _libraries-caching-configuring-the-cache:
+
 *********************
 Configuring the Cache
 *********************