SubmittingPatches: explain rationale for using --notes with format-patch

diff --git a/RelNotes b/RelNotes
index 2bff7b20de8972e2a8cf9bf7a8cea4ff2e9789f1..c5fa3efb98246d99bdf736237b7cf759f01a1657 120000 (symlink)
--- a/RelNotes
+++ b/RelNotes
@@ -1 +1 @@
-Documentation/RelNotes/1.9.4.txt
\ No newline at end of file
+Documentation/RelNotes/2.2.2.txt
\ No newline at end of file