Add link to v1.5.0 documentation.

Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/git.txt

@@ -35,6 +35,10 @@ ifdef::stalenotes[]
 You are reading the documentation for the latest version of git.
 Documentation for older releases are available here:
 
+* link:v1.5.0/git.html[documentation for release 1.5.0]
+
+* link:v1.5.0/RelNotes-1.5.0.txt[release notes for 1.5.0]
+
 * link:v1.4.4.4/git.html[documentation for release 1.4.4.4]
 
 * link:v1.3.3/git.html[documentation for release 1.3.3]