[master] ec26d972f upgrading-8.0.rst: Mention more breaking changes

[Walid Boudebouda]

commit ec26d972f2ddb241b12904aa325c73252bd5abab
Author: Walid Boudebouda <walid.boudebouda at gmail.com>
Date:   Mon Sep 15 11:46:35 2025 +0200

    upgrading-8.0.rst: Mention more breaking changes

diff --git a/doc/sphinx/whats-new/upgrading-8.0.rst b/doc/sphinx/whats-new/upgrading-8.0.rst
index 3dc4f01e4..c3295c8c0 100644
--- a/doc/sphinx/whats-new/upgrading-8.0.rst
+++ b/doc/sphinx/whats-new/upgrading-8.0.rst
@@ -11,6 +11,46 @@ please refer to the `change log`_ or :ref:`whatsnew_changes_8.0`.
 
 .. _change log: https://github.com/varnishcache/varnish-cache/blob/master/doc/changes.rst
 
+varnishd
+========
+
+Unknown HTTP methods handling
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+In previous versions of Varnish, requests with an unknown/unsupported HTTP
+method were by default piped to the backend. Starting with Varnish 8.0, the
+default behaviour for such requests is to return a synthetic 501 response and
+close the connection. Handling of custom HTTP methods can of course still be
+implemented in your VCL.
+
+Parameter aliases
+~~~~~~~~~~~~~~~~~
+
+It is no longer possible to set a parameter alias as read only, instead the
+actual parameter that it refers to should be set directly.
+
+Other changes in varnishd
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The ``Content-Length`` response header is now also sent in response to all
+``HEAD`` requests.
+
+Request body read failures now result in a ``400`` response status.
+
+Bans
+====
+
+The default value of the ``ban_any_variant``parameter was changed to 0.
+This means that during a lookup, only the matching variants of an object will be
+evaluated against the ban list.
+As a side effect, variants that are rarely requested may never get a chance to
+be tested against ``req`` based bans, which can lead to an accumulation of bans
+over time. In such cases, it is recommended to set ``ban_any_variant`` to a
+higher value.
+You can also consider using the new ``obj.last_hit`` ban variable to evict such
+objects.
+
+
 vmod_std changes
 ================