[css-logical-1] Fix duplicate ID

Author: fantasai

css-logical-1/Overview.bs

@@ -438,7 +438,7 @@ the 'margin-block-start', 'margin-block-end', 'margin-inline-start', 'margin-inl
   and the second value represents the <a>end</a> edge style.
   If only one value is given, it applies to both the <a>start</a> and <a>end</a> edges.
 
-<h3 id="inset-properties">
+<h3 id="position-properties">
 Flow-relative Offsets:
 the 'inset-block-start', 'inset-block-end', 'inset-inline-start', 'inset-inline-end' properties and 'inset-block', 'inset-inline', and 'inset' shorthands</h3>