[css-text-decor-4] Fix typo

Author: fantasai

css-text-decor-4/Overview.bs

@@ -391,7 +391,7 @@ Text Decoration Line Continuity: the 'text-decoration-skip-ink' property</h4>
 	</dl>
 
 <h2 id="text-shadow-property">
-Additional Conrols for Text Shadows</h2>
+Additional Controls for Text Shadows</h2>
 
 	Level 4 adds a spread radius argument to 'text-shadow',
 	using the same syntax and interpretation as for 'box-shadow',