update release note for 2.02.6

Author: RichardGe

release_notes.txt

@@ -22,7 +22,9 @@ RPRNEXT-379 - (Bug)      - Fix light leak on mesh light
    This argument can be set to NULL in order to have the same behavior than before 2.02.6.
 
  * new material for Northstar: RPR_MATERIAL_NODE_BLACKBODY.
-   inputs of : RPR_MATERIAL_INPUT_TEMPERATURE , RPR_MATERIAL_INPUT_KELVIN , RPR_MATERIAL_INPUT_EMISSION.
+   inputs of : RPR_MATERIAL_INPUT_TEMPERATURE , RPR_MATERIAL_INPUT_KELVIN.
+
+ * C# header is fixed
 
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 RPR SDK 2.02.5 - 09 July 2021