git.html: Update the links to stale versions

Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/git.txt

@@ -43,9 +43,11 @@ unreleased) version of git, that is available from 'master'
 branch of the `git.git` repository.
 Documentation for older releases are available here:
 
-* link:v1.6.0.2/git.html[documentation for release 1.6.0.2]
+* link:v1.6.0.4/git.html[documentation for release 1.6.0.4]
 
 * release notes for
+  link:RelNotes-1.6.0.4.txt[1.6.0.4],
+  link:RelNotes-1.6.0.3.txt[1.6.0.3],
   link:RelNotes-1.6.0.2.txt[1.6.0.2],
   link:RelNotes-1.6.0.1.txt[1.6.0.1],
   link:RelNotes-1.6.0.txt[1.6.0].