feature #3774 [Book][Internals] add description for the kernel.finish…

…_request event (xabbuh)

This PR was merged into the 2.4 branch.

Discussion
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[Book][Internals] add description for the kernel.finish_request event

| Q             | A
| ------------- | ---
| Doc fix?      | no
| New docs?     | yes
| Applies to    | 2.4+
| Fixed tickets | #2959

Commits
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f02fb35 [Book][Internals] add description for the kernel.finish_request event

book/internals.rst

@@ -364,6 +364,19 @@ The FrameworkBundle registers several listeners:
 
     Read more on the :ref:`kernel.response event <component-http-kernel-kernel-response>`.
 
+.. index::
+    single: Event; kernel.finish_request
+
+``kernel.finish_request`` Event
+...............................
+
+*Event Class*: :class:`Symfony\\Component\\HttpKernel\\Event\\FinishRequestEvent`
+
+The purpose of this event is to to handle tasks that should be performed after
+the request has been handled but that do not need to modify the response.
+Event listeners for the ``kernel.finish_request`` event are called in both
+successful and exception cases.
+
 .. index::
    single: Event; kernel.terminate