minor #15445 [Cache] Adds a heading for stampede prevention so I'm able to reference this section easily (smoench)

This PR was merged into the 4.4 branch.

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[Cache] Adds a heading for stampede prevention so I'm able to reference this section easily

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d3cb9b5 Adds a heading for stampede prevention so I'm able to reference this section easily

Author: javiereguiluz

components/cache.rst

@@ -90,6 +90,9 @@ generate and return the value::
     Use cache tags to delete more than one key at the time. Read more at
     :doc:`/components/cache/cache_invalidation`.
 
+Stampede prevention
+~~~~~~~~~~~~~~~~~~~
+
 The Cache Contracts also comes with built in `Stampede prevention`_. This will
 remove CPU spikes at the moments when the cache is cold. If an example application
 spends 5 seconds to compute data that is cached for 1 hour and this data is accessed