submodule: whitespace fix

diff --git a/RelNotes b/RelNotes
index 5fcc4ef74770e8587a1469fff5e3f5610dabf0e1..6372427426d80b01b03437fd1a55fd412fb8f75d 120000 (symlink)
--- a/RelNotes
+++ b/RelNotes
@@ -1 +1 @@
-Documentation/RelNotes/1.7.6.txt
\ No newline at end of file
+Documentation/RelNotes/1.7.7.txt
\ No newline at end of file