Add Animation Blend modes constants to documentation (#24428)

Co-authored-by: decuyper <[email protected]>

docs/api/en/constants/Animation.html

@@ -29,6 +29,12 @@ THREE.InterpolateSmooth
 THREE.ZeroCurvatureEnding
 THREE.ZeroSlopeEnding
 THREE.WrapAroundEnding
+    </code>
+
+	<h2>Animation Blend Modes</h2>
+    <code>
+THREE.NormalAnimationBlendMode
+THREE.AdditiveAnimationBlendMode
     </code>
 
 		<h2>Source</h2>