changes: Split a strands of hair

Reverting "retrieving" to "processing" is motivated by the fact that we
process ESI on the client side and we don't know whether we are in fact
retrieving an object from a backend, or just reusing one from the cache.

Even if the word "processing" appears again in the sentence, I think it
is more accurate here.

Better diff with the --word-diff option.

doc/changes.rst

@@ -51,16 +51,16 @@ Varnish Cache NEXT (2024-03-15)
   ``sess.send_timeout`` can now be ``unset`` to use their default
   values from parameters.
 
-* Timeout and deadline parameters and VCL variables can now be set to
-  the special value ``never`` to apply an infinitely long
-  timeout. Parameters which used to be of type ``timeout`` but do not
-  accept ``never`` have been moved to the new type ``duration``.
+* Timeout and deadline parameters can now be set to a new special value
+  ``never`` to apply an infinitely long timeout. Parameters which used to
+  be of type ``timeout`` but do not accept ``never`` have been moved to
+  the new type ``duration``. VCL variables cannot be set to ``never``.
 
-* The implementation of the feature flag ``esi_include_onerror`` added
+* The implementation of the feature flag ``esi_include_onerror`` changed
   in Varnish-Cache 7.3.0 has been reverted to more closely match the
   behavior before that release: By default, fragments are included
   again, even errors. When ``esi_include_onerror`` is enabled and
-  errors are encountered while retrieving an ESI fragment, processing
+  errors are encountered while processing an ESI fragment, processing
   only continues if the ``onerror`` attribute of the ``<esi:include>``
   tag is present.
 
@@ -109,7 +109,8 @@ Varnish Cache NEXT (2024-03-15)
   function with a zero ``sz`` argument.
 
 * The ``Timestamp`` SLT with ``Process`` prefix is not emitted any
-  more when processing continues as for restarts.
+  more when processing continues as for restarts, or when ``vcl_deliver``
+  transitions to ``vcl_synth``.
 
 * The ``FetchError`` SLT with ``HTC`` prefix now contains a verbose
   explanation.