Teach --recursive to submodule sync

diff --git a/RelNotes b/RelNotes
index 8ee12bf8a31a83289e4be3b0bbba88b5775ac7c9..2484b38bbbae654684f65a874653487439f0df2f 120000 (symlink)
--- a/RelNotes
+++ b/RelNotes
@@ -1 +1 @@
-Documentation/RelNotes/1.7.12.2.txt
\ No newline at end of file
+Documentation/RelNotes/1.8.0.txt
\ No newline at end of file