Changes:
* fix broken links
* add link to release notes
Change-Id: I01b360bab2ea08f3f940ea5992ac6981b68074b5
Useful links
------------
-* More about rally: https://rally.readthedocs.org/en/latest/
+* More about Rally: https://rally.readthedocs.org/en/latest/
-* How to add rally-gates: https://rally.readthedocs.org/en/latest/rally_gatejob.html
+* Rally release notes: https://rally.readthedocs.org/en/latest/release_notes.html
-* About plugins: https://rally.readthedocs.org/en/latest/plugins.html
+* How to add rally-gates: https://rally.readthedocs.org/en/latest/gates.html
-* Plugin samples: https://github.com/stackforge/rally/tree/master/doc/samples/plugins
+* About plugins: https://rally.readthedocs.org/en/latest/plugins.html
+* Plugin samples: https://github.com/openstack/rally/tree/master/samples/plugins