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/faq.rst b/doc/source/faq.rst
index f39471c..92d7945 100644
--- a/doc/source/faq.rst
+++ b/doc/source/faq.rst
@@ -123,7 +123,7 @@
     [STRIKEOUT:The majority of deployments will use packages to install
     OpenStack that will have distro-based packages as dependencies.
     DevStack installs as many of these Python packages as possible to
-    mimic the expected production environemnt.] Certain Linux
+    mimic the expected production environment.] Certain Linux
     distributions have a 'lack of workaround' in their Python
     configurations that installs vendor packaged Python modules and
     pip-installed modules to the SAME DIRECTORY TREE. This is causing