minor symfony#11830 Fix new instance of a class name (peaceant)

This PR was submitted for the 4.3 branch but it was merged into the 3.4 branch instead (closes symfony#11830).

Discussion
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Fix new instance of a class name

Fix for symfony#11824

Commits
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c08a0e3 Fix new instance of a class name

Author: javiereguiluz

components/cache/psr6_psr16_adapters.rst

@@ -80,7 +80,7 @@ this use-case::
     $psr6Cache = new FilesystemAdapter();
 
     // a PSR-16 cache that uses your cache internally!
-    $psr16Cache = new Psr6Cache($psr6Cache);
+    $psr16Cache = new Psr16Cache($psr6Cache);
 
     // now use this wherever you want
     $githubApiClient = new GitHubApiClient($psr16Cache);