Update versions/3.1.1.md

Co-authored-by: Ralf Handl <[email protected]>

Author: handrews

versions/3.1.1.md

@@ -2933,7 +2933,7 @@ additionalProperties:
 
 ```yaml
   oneOf:
-  - const: rgb
+  - const: RGB
     title: Red, Green, Blue
     description: Specify colors with the red, green, and blue additive color model
   - const: cmyk