trivial: Fix typos in the documentation page

This patchset fixes typos (capitalization mistakes,
grammar mistakes) found in the documentation pages.

Change-Id: If500aeab1af7dd8b56d63cbc481ee501216df161
diff --git a/doc/source/write_tests.rst b/doc/source/write_tests.rst
index fff2405..0a29b7b 100644
--- a/doc/source/write_tests.rst
+++ b/doc/source/write_tests.rst
@@ -4,7 +4,7 @@
 ##########################
 
 This guide serves as a starting point for developers working on writing new
-Tempest tests. At a high level tests in Tempest are just tests that conform to
+Tempest tests. At a high level, tests in Tempest are just tests that conform to
 the standard python `unit test`_ framework. But there are several aspects of
 that are unique to Tempest and its role as an integration test suite running
 against a real cloud.