Tiny change for lispref "Reverting"

* doc/lispref/backups.texi (Reverting):
Un-duplicate revert-buffer-in-progress-p, and relocate entry.
Mention buffer-stale-function.
* doc/emacs/arevert-xtra.texi: Comment.

1 files changed, 16 insertions, 6 deletions

diff --git a/doc/lispref/backups.texi b/doc/lispref/backups.texi
index 2bcb768aea..a1c5f20f28 100644
--- a/doc/lispref/backups.texi
+++ b/doc/lispref/backups.texi
@@ -699,11 +699,13 @@ operation, reverting preserves all the markers.  If they are not
 identical, reverting does change the buffer; in that case, it preserves
 the markers in the unchanged text (if any) at the beginning and end of
 the buffer.  Preserving any additional markers would be problematical.
-
-This command binds @code{revert-buffer-in-progress-p} to a
-non-@code{nil} value while it operates.
 @end deffn
 
+@defvar revert-buffer-in-progress-p
+@code{revert-buffer} binds this variable to a non-@code{nil} value
+while it is working.
+@end defvar
+
 You can customize how @code{revert-buffer} does its work by setting
 the variables described in the rest of this section.
 
@@ -758,7 +760,15 @@ the modified contents---but only if @code{revert-buffer-function} is
 @code{nil}.
 @end defvar
 
-@defvar revert-buffer-in-progress-p
-This variable is bound to a non-@code{nil} value by
-@code{revert-buffer} while it is working.
+@c FIXME?  Move this section from arevert-xtra to here?
+@defvar buffer-stale-function
+The value of this variable, if non-@code{nil}, specifies a function
+to call to check whether a non-file buffer needs reverting
+@iftex
+(@pxref{Supporting additional buffers,,, emacs-xtra,  Specialized Emacs Features}).
+@end iftex
+@ifnottex
+(@pxref{Supporting additional buffers,,, emacs}).
+@end ifnottex
 @end defvar
+