Several small improvements for README

* fix typos
* fix link

Change-Id: I187a6c42e8db2dd52c37a8b169fe22fcbf77acd9

README.rst

@@ -1,6 +1,6 @@
-=====
+===============
 rally-openstack
-=====
+===============
 
 Rally plugins for `OpenStack platform <https://openstack.org>`_
 
@@ -14,7 +14,7 @@ Usage
     pip install rally-openstack
 
     # List all installed plugins
-    rally plugin --platform openstack
+    rally plugin list --platform openstack
 
     # Create OpenStack Env
 
@@ -38,7 +38,7 @@ Usage
     # Collect key Open Stack metrics
     rally task start ./tasks/openstack_metrics/task.yaml --task-args {"image_name": "image_to_use", "flavor_name": "flavor_to_use"}
 
-    # Generate Repot
+    # Generate Report
     rally task report --out report.html
 
 
@@ -47,7 +47,7 @@ Links
 
 * Free software: Apache license
 * Documentation: https://rally.readthedocs.org/en/latest/
-* Source: https://git.openstack.org/cgit/openstack/rally
+* Source: https://git.openstack.org/cgit/openstack/rally-openstack
 * Bugs: https://bugs.launchpad.net/rally
 * Step-by-step tutorial: https://rally.readthedocs.io/en/latest/quick_start/tutorial.html
 * Launchpad page: https://launchpad.net/rally