core-tutorial: correct URL

The tinyurl is incorrect -- it attempts to go to groups.osdl.org,
which is gone.  Either use the full URL (in patch) or create a new
tinyurl for this URL.

Is the web page (where I first saw this problem) generated from
this txt file?
http://www.kernel.org/pub/software/scm/git/docs/core-tutorial.html
If not, it needs to be updated also.
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/core-tutorial.txt

@@ -1459,7 +1459,8 @@ Although git is a truly distributed system, it is often
 convenient to organize your project with an informal hierarchy
 of developers. Linux kernel development is run this way. There
 is a nice illustration (page 17, "Merges to Mainline") in
-link:http://tinyurl.com/a2jdg[Randy Dunlap's presentation].
+link:http://www.xenotime.net/linux/mentor/linux-mentoring-2006.pdf
+[Randy Dunlap's presentation].
 
 It should be stressed that this hierarchy is purely *informal*.
 There is nothing fundamental in git that enforces the "chain of