* lisp/mail/sendmail.el (mail-position-on-field): Doc fix.

lisp/mail/sendmail.el

@@ -1500,9 +1500,10 @@ just append to the file, in Babyl format if necessary."
            (insert "\nMail-Followup-To: "))))
 
 (defun mail-position-on-field (field &optional soft)
-  "Move to the start of the contents of header field FIELD.
-If there is none, insert one, unless SOFT is non-nil.
-If there are multiple FIELD fields, this goes to the first."
+  "Move to the end of the contents of header field FIELD.
+If there is no such header, insert one, unless SOFT is non-nil.
+If there are multiple FIELD fields, this goes to the first.
+Returns non-nil if FIELD was originally present."
   (let (end
 	(case-fold-search t))
     (setq end (mail-header-end))