Update rally link

Update rally link to the correct path.

Change-Id: Ifeee881465f812527eab4cc191c2140b803a613a

doc/source/developing_guides/rally_on_gates.rst

@@ -71,8 +71,7 @@ placed in ``rally-scenarios/extra/`` directory.
 
 Also it's possible to specify other fields for each Rally task, like ``sla``
 or ``context``. More information about other configuration setting is
-available by link https://rally.readthedocs.org/en/latest/tutorial.html
-
+available by link https://rally.readthedocs.io/en/latest/plugins/#rally-plugins
 Mentioned patch was proposed for confirmation caching mechanism of Heat
 template validation process
 (see https://specs.openstack.org/openstack/heat-specs/specs/liberty/constraint-validation-cache.html).

rally-scenarios/README.rst

@@ -10,4 +10,4 @@ Structure:
 
 * more about rally: https://wiki.openstack.org/wiki/Rally
 * how to add rally-gates: https://wiki.openstack.org/wiki/Rally/RallyGates
-* how to write plugins https://rally.readthedocs.org/en/latest/plugins.html
+* how to write plugins https://rally.readthedocs.io/en/latest/plugins/#rally-plugins

rally-scenarios/plugins/sample_plugin.py

@@ -18,7 +18,7 @@
 For more Heat related benchmarks take a look here:
 https://git.openstack.org/cgit/openstack/rally/tree/rally/plugins/openstack/scenarios/heat
 
-About plugins: https://rally.readthedocs.org/en/latest/plugins.html
+About plugins: https://rally.readthedocs.io/en/latest/plugins/#rally-plugins
 
 Rally concepts https://wiki.openstack.org/wiki/Rally/Concepts
 """