Make the manual say what undo-auto-amalgamate does

* doc/lispref/text.texi (Undo): Say what undo-auto-amalgamate does
in addition to describing what amalgamation is (bug#35344).

1 files changed, 4 insertions, 0 deletions

diff --git a/doc/lispref/text.texi b/doc/lispref/text.texi
index ca0dd6642d9..94b94eaba7e 100644
--- a/doc/lispref/text.texi
+++ b/doc/lispref/text.texi
@@ -1408,6 +1408,10 @@ Where a command affects the contents of several buffers, as may happen,
 for example, when a function on the @code{post-command-hook} affects a
 buffer other than the @code{current-buffer}, then @code{undo-boundary}
 will be called in each of the affected buffers.
+
+This function can be called before an amalgamating command.  It
+removes the previous @code{undo-boundary} if a series of such calls
+have been made.
 @end defun
 
 @defvar undo-auto-current-boundary-timer