Merge pull request #4029 from segmentio/Transformations-clarification

Transformations clarification

Author: rchinn1

src/protocols/transform/index.md

@@ -112,7 +112,7 @@ Here's a list of Segment Transformations with some use case examples.
 
 - **Update a property value:** Use [Segment's Public API](https://docs.segmentapis.com/tag/Transformations){:target="_blank"} to transform the property `currency` to have the value `USD`. 
 
-- **Add a new property name and assign a value:** If you want to create a new property and set a static value, use [Segment's Public API](https://docs.segmentapis.com/tag/Transformations){:target="_blank"} to create `new_property: static_value`.
+- **Add a new property name and assign a value:** If you want to create a new property and set a static value, use [Segment's Public API](https://docs.segmentapis.com/tag/Transformations){:target="_blank"} to create `new_property: static_value`. Segment currently supports setting static values for top-level fields with `propertyValueTransformations`. However, Segment doesn't support changing fields outside the properties or traits object with `propertyRenames`.
 
 {% comment %}
 - **Change property value casing:** Transform property value casing to lowercase, uppercase, or title case. For example, Transform the property value `united states` to `USA` to remain consistent with your data tracking.