DOCSP-23936 Fixes typo (#86)

Author: kennethdyer

source/includes/fact-atlas-roles.rst

@@ -4,7 +4,7 @@ The user specified in the connection string must have, at a minimum, the
 .. note:: 
 
    To use ``mongosync`` in the :ref:`reverse direction <c2c-api-reverse>`,
-   you must :atlas:`create a custum role 
+   you must :atlas:`create a custom role 
    </reference/api/custom-roles-create-a-role>` that grants the
    following ActionTypes: