minor #11772 Use valid number of backslashes, depending on 1 or 2 ticks - 4.2 (OskarStark)

This PR was merged into the 4.2 branch.

Discussion
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Use valid number of backslashes, depending on 1 or 2 ticks - 4.2

Needs rebase after #11771

Commits
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501c509 Use valid number of backslashes, depending on 1 or 2 ticks

Author: OskarStark

components/cache/cache_items.rst

@@ -42,7 +42,7 @@ pool::
     // $cache pool object was created before
     $productsCount = $cache->getItem('stats.products_count');
 
-Then, use the ``Psr\\Cache\\CacheItemInterface::set`` method to set the data stored
+Then, use the ``Psr\Cache\CacheItemInterface::set`` method to set the data stored
 in the cache item (this step is done automatically when using the Cache Contracts)::
 
     // storing a simple integer

messenger/multiple_buses.rst

@@ -209,7 +209,7 @@ the correct tag:
 
         # config/services.yaml
 
-        # put this after the `App\` line that registers all your services
+        # put this after the "App\" line that registers all your services
         command_handlers:
             namespace: App\MessageHandler\
             resource: '%kernel.project_dir%/src/MessageHandler/*CommandHandler.php'