Add NEWS entry for bug-reference auto-setup.

* etc/NEWS: Add entry for bug-reference auto-setup.

etc/NEWS

@@ -404,7 +404,6 @@ To enable, add it to appropriate entries in 'c-offsets-alist', e.g.:
 ** browse-url
 
 *** Added support for custom URL handlers.
-
 There is a new variable 'browse-url-default-handlers' and a user
 option 'browse-url-handlers' being alists with '(REGEXP-OR-PREDICATE
 . FUNCTION)' entries allowing to define different browsing FUNCTIONs
@@ -418,7 +417,6 @@ Formerly, one could do the same by setting
 supported but deprecated.
 
 *** Categorization of browsing functions in internal vs. external.
-
 All standard browsing functions such as 'browse-url-firefox',
 'browse-url-mail', or 'eww' have been categorized into internal (URL
 is browsed in Emacs) or external (an external application is spawned
@@ -504,6 +502,21 @@ the function 'format-spec' documented under node "(elisp) Custom Format
 Strings".  The new syntax includes specifiers for padding and
 truncation, amongst other things.
 
+** bug-reference.el
+
+---
+*** Bug reference mode auto-setup.  If 'bug-reference-mode' or
+'bug-reference-prog-mode' have been activated, their respective hook
+has been run and still 'bug-reference-bug-regexp' and
+'bug-reference-url-format' aren't both set, it tries to guess
+appropriate values for those two variables.  There are two guessing
+mechanisms so far: based on version control information of the current
+buffer's file, and based on newsgroup/mail-folder name and several
+news and mail message headers in Gnus buffers.  Both mechanisms are
+extensible with custom rules, see the variables
+'bug-reference-setup-from-vc-alist' and
+'bug-reference-setup-from-mail-alist'.
+
 
 * New Modes and Packages in Emacs 28.1