[css-gcpm-4][editorial] Fix bikeshed markup

Author: fantasai

css-gcpm-4/Overview.bs

@@ -55,7 +55,7 @@ Headers often contain document content, and it is desirable to both display that
 
 <pre class="propdef">
 Name: copy-into
-Value: none |  [ [ &lt;custom-ident>  &lt;content-level>] [,  &lt;custom-ident>  &lt;content-level>]*  ]?
+Value: none |  [ [ <<custom-ident>>  <<content-level>>] [,  <<custom-ident>>  <<content-level>>]*  ]?
 Initial: none
 Applies To: all elements and pseudo-elements, but not ::first-line or ::first-letter.
 Inherited: no
@@ -65,10 +65,10 @@ Animation type: discrete
 
 The 'copy-into' property contains one or more pairs, each consisting of a custom identifier followed by a content-level keyword describing how to construct the value of the named content fragment.
 
-''content-level'' expands to the following values:
+<<content-level>> expands to the following values:
 
 <pre class="prod">
-	<dfn id="content-list">content-list</dfn> = element | content | text | attr(&lt;identifier>) | counter() | counters()
+    <dfn><<content-level>></dfn> = element | content | text | <<attr()>> | <<counter>>
 </pre>
 
 
@@ -77,7 +77,7 @@ The 'copy-into' property contains one or more pairs, each consisting of a custom
 <dd>the entire element is copied into the named content fragment</dd>
 
 <dt>contents</dt>
-<dd>only the element’s contents are copied into the named content fragment. This is the default if ''content-level'' is not specified.</dd>
+<dd>only the element’s contents are copied into the named content fragment. This is the default if <<content-level>> is not specified.</dd>
 
 <dt>text</dt>
 <dd>only the element’s text (including normally collapsed white space) is copied into the named content fragment.</dd>