fix typo

Co-authored-by: Jeremy Roman <jeremy@jeremyroman.com>

Author: frivoal

css-ui-4/Overview.bs

@@ -1094,7 +1094,7 @@ Insertion caret</h3>
 	with a similar appearance,
 	also occasionally referred to as “carets”.
 	For example, some UAs can show a “navigation caret”,
-	which acts similarly to an [insertion caret=]
+	which acts similarly to an [=insertion caret=]
 	but can be moved around in non-editable text.
 	The 'caret-color', 'caret-animation', and 'caret-shape' properties
 	are not intended to apply to such mechanisms