bug#81547: 31.0.90; Defcustom's docstring does not mention new `BUFFER-LOCAL' optional argument for :set function

> From: Antonio Romano <[email protected]>
> Date: Mon, 03 Aug 2026 21:25:47 +0000
> 
> According to NEWS:
> 
> ---
> ** New macro 'setopt-local'.
> This is the buffer-local version of 'setopt' for user options rather
> than plain variables and uses 'custom-set'/'set-local' to set variable
> values.  A new argument, BUFFER-LOCAL, is passed to 'custom-set'
> functions to indicate the buffer-local context.
> ---
> 
> However, this is currently `defcustom' docstring regarding `:set':
> 
> ---
> :set	VALUE should be a function to set the value of the symbol
> 	when using the Customize user interface.  It takes two arguments,
> 	the symbol to set and the value to give it.  The function should
> 	not modify its value argument destructively.  The default choice
> 	of function is `set-default-toplevel-value'.  If this keyword is
> 	defined, modifying the value of SYMBOL via `setopt' will call the
> 	function specified by VALUE to install the new value.
> ---
> 
> When it now takes two arguments plus an optional argument called
> BUFFER-LOCAL that is non-nil when the value is set through
> `setopt-local'.

Thanks, fixed on the emacs-31 release branch.