runtime(doc): clarify the effect of 'startofline' option

fixes: #15794

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/motion.txt b/runtime/doc/motion.txt
index 99fd3e2..2637480 100644
--- a/runtime/doc/motion.txt
+++ b/runtime/doc/motion.txt
@@ -1,4 +1,4 @@
-*motion.txt*    For Vim version 9.1.  Last change: 2024 Oct 05
+*motion.txt*    For Vim version 9.1.  Last change: 2024 Oct 06
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -68,10 +68,12 @@
 or after the first character, that many lines are operated upon.  Thus `3dd`
 deletes three lines. A count before and after the first character is
 multiplied, thus `2y3y` yanks six lines.
-
+						*operator-resulting-pos*
 After applying the operator the cursor is mostly left at the start of the text
 that was operated upon.  For example, "yfe" doesn't move the cursor, but "yFe"
 moves the cursor leftwards to the "e" where the yank started.
+The 'startofline' option applies only to the "d", "<<", "==" and ">>" linewise
+operations.
 
 						*linewise* *characterwise*
 The operator either affects whole lines, or the characters between the start