Add clarification of attribute path.

Author: MarkvanMents

content/en/docs/refguide/modeling/xpath/xpath-constraints/xpath-constraint-functions/_index.md

@@ -23,3 +23,7 @@ The following pages describe the functions that can be executed within constrain
 * [contains](/refguide/xpath-contains/)
 * [starts-with](/refguide/xpath-starts-with/)
 * [ends-with](/refguide/xpath-ends-with/)
+
+{{% alert color="info" %}}
+In all these functions, the attribute in the example is just the name of the attribute, for example `Name`. This is for clarity. However, the attribute can also contain the path to the attribute, for example `Sales.Order_Customer/Name`.
+{{% /alert %}}