docs: issue2551398 document enabling native browser number/integer types

The original default was to have them enabled. Due to issues with
locale (e.g. decimal thousands separator vs comma seperator) this is
disabled by default. See issue for details.

Author: rouilj

doc/upgrading.txt

@@ -362,11 +362,11 @@ There is no support for activating text mode using the
 keyboard. Tablet/touch support is mixed. Chrome supports
 double-tap to activate text mode input. Firefox does not.
 
-Revert native number inputs for Number() and Integer() (optional)
+Enable native number inputs for Number() and Integer() (optional)
 -----------------------------------------------------------------
 
 Roundup's ``field()`` method for properties of type ``Number()`` or
-``Integer()`` now use a native browser number input by default.
+``Integer()`` can use a native browser number input by default.
 
 This is configurable for *all* ``Number()`` and ``Integer()`` properties
 with the config option ``use_browser_number_input`` in section ``[web]``.
@@ -379,6 +379,8 @@ add a stepper control and try to constrain the input to
 integers. This can be overridden by passing a new step
 (e.g. ``step="50"``) to the ``field()`` method.
 
+This is an experiment and maybe changed based on feedback.
+
 Change in REST response for invalid CORS requests (info)
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