Update source/upgrade/v3.txt

Author: mongoKart

source/upgrade/v3.txt

@@ -61,7 +61,7 @@ Version 3.0 Breaking Changes
   and {+mdb-server+} versions, visit the
   :ref:`Compatibility <csharp-compatibility-tables>` page.
 
-- The classes, methods, and properties ``MongoDB.Driver.Core`` namespace that were
+- The classes, methods, and properties in the ``MongoDB.Driver.Core`` namespace that were
   deprecated in v{+last-version-2-number+} are marked ``internal``. If the driver
   provides a replacement for a deprecated class, method, or property, the compiler
   messages in v{+last-version-2-number+} will display it.