[css-anchor-1] An actual introduction (moved existing text)

Author: svgeesus

css-anchor-1/Overview.bs

@@ -42,11 +42,6 @@ spec:css-cascade-5; type:dfn; text:property
 Introduction {#intro}
 =====================
 
-Introduction here.
-
-Anchoring {#anchoring}
-==================================
-
 While CSS generally determines the position and size of elements
 according to their parents or other ancestors,
 [=absolutely positioned=] elements barely participate in their ancestors' layout.
@@ -61,6 +56,9 @@ but in return it's not very expressive--
 the element cannot easily express its size and position
 in terms of other elements on the page.
 
+Anchoring {#anchoring}
+==================================
+
 The <dfn export lt="anchor function">anchor functions</dfn>
 ''anchor()'' and ''anchor-size()'',
 defined below,