Fix typo errors in devstack documentation

This submission fixes typo errors in following files
  1. contributing.rst
  2. exerciserc.rst
  3. faq.rst
  4. local.conf.rst
  5. openrc.rst

Change-Id: I2b2d61673c3c95f60c56978b5a81016603fef252
diff --git a/doc/source/openrc.rst b/doc/source/openrc.rst
index 56ff5c2..0b090c7 100644
--- a/doc/source/openrc.rst
+++ b/doc/source/openrc.rst
@@ -4,7 +4,7 @@
 
 ``openrc`` configures login credentials suitable for use with the
 OpenStack command-line tools. ``openrc`` sources ``stackrc`` at the
-beginning (which in turn sources the ``localrc`` setion of
+beginning (which in turn sources the ``localrc`` section of
 ``local.conf``) in order to pick up ``HOST_IP`` and/or ``SERVICE_HOST``
 to use in the endpoints. The values shown below are the default values.