Add missing help for text-transform math test. (#17686)
diff --git a/css/css-text/text-transform/math/text-transform-math-auto-002.tentative.html b/css/css-text/text-transform/math/text-transform-math-auto-002.tentative.html
index 86c1ea1..32bad74 100644
--- a/css/css-text/text-transform/math/text-transform-math-auto-002.tentative.html
+++ b/css/css-text/text-transform/math/text-transform-math-auto-002.tentative.html
@@ -4,6 +4,7 @@
<meta charset="utf-8"/>
<title>text-transform math-auto</title>
<link rel="help" href="https://github.com/w3c/csswg-drafts/issues/3745"/>
+<link rel="help" href="https://mathml-refresh.github.io/mathml-core/#new-text-transform-values">
<link rel="match" href="text-transform-math-auto-002.tentative-ref.html"/>
<meta name="assert" content="Test 'text-transform: math-auto' for text nodes of different lengths">
<style>
