diff-index.c: "git diff" has no need to read blob from the standard input

diff --git a/RelNotes b/RelNotes
index f84c4c7f11b0d2df58151efc5dcc01da4ebd4be6..fb9320b14baeae5fdb759a99e7edb77546cd5bc1 120000 (symlink)
--- a/RelNotes
+++ b/RelNotes
@@ -1 +1 @@
-Documentation/RelNotes-1.5.4.4.txt
\ No newline at end of file
+Documentation/RelNotes/1.7.6.6.txt
\ No newline at end of file