minor #6588 Update configuration.rst (superhaggis)

This PR was submitted for the 3.0 branch but it was merged into the 2.3 branch instead (closes #6588).

Discussion
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Update configuration.rst

Slight grammatical tweak.

Commits
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07c0730 Update configuration.rst

cookbook/bundles/configuration.rst

@@ -373,7 +373,7 @@ can place it anywhere you like. You should return this path as the base path::
         }
     }
 
-Assume the XSD file is called ``hello-1.0.xsd``, the schema location will be
+Assuming the XSD file is called ``hello-1.0.xsd``, the schema location will be
 ``http://acme_company.com/schema/dic/hello/hello-1.0.xsd``:
 
 .. code-block:: xml