Update CHANGELOG

CHANGELOG

@@ -3,6 +3,17 @@ changelog
 
 Current Release:    raylib 3.7.0 (26 April 2021)
 
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+Release:     raylib 4.0 (November? 2021)
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+KEY CHANGES:
+ - 
+ - 
+ - 
+ 
+Detailed changes:
+
+
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 Release:     raylib 3.7 (26 April 2021)
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