Updated v3 release notes (markdown)

v3-release-notes.md

@@ -88,7 +88,40 @@ TODO
 
 ### Enum inputs
 
-TODO
+As outlined above: if a field takes an Enum as an input the resolver will now get passed the Enum member rather than the member value. 
+
+For example, given the following schema:
+
+```python
+from graphene import Enum, ObjectType, String, Schema
+
+class Color(Enum):
+    RED = 1
+    GREEN = 2
+    BLUE = 3
+
+class Query(ObjectType):
+    color = String(color_input=Color(required=True))
+
+    def resolve_color(root, info, color_input):
+        return color_input
+
+schema = Schema(query=Query)
+```
+
+Before:
+
+```python
+result = schema.execute("query { color(colorInput: RED) }")
+assert result.data["color"] == "1"
+```
+
+After:
+
+```python
+result = schema.execute("query { color(colorInput: RED) }")
+assert result.data["color"] == "EnumMeta.RED"
+```
 
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