[css-backgrounds-3] Move <bg-color> to the end of the <final-bg-layer> component. w3c#8496

Author: tabatkins

css-backgrounds-3/Overview.bs

@@ -973,9 +973,9 @@ Animation type: see individual properties
 
 <p>Where
 
-<pre class=prod><dfn><<bg-layer>></dfn> = <<bg-image>> || <<bg-position>> [ / <<bg-size>> ]? || <<repeat-style>> || <<attachment>> || <<box>> || <<box>></pre>
-
-<pre class=prod><dfn><<final-bg-layer>></dfn> =  <<'background-color'>> || <<bg-image>> || <<bg-position>> [ / <<bg-size>> ]? || <<repeat-style>> || <<attachment>> || <<box>> || <<box>></pre>
+<pre class=prod>
+<dfn>&lt;bg-layer></dfn> = <<bg-image>> || <<bg-position>> [ / <<bg-size>> ]? || <<repeat-style>> || <<attachment>> || <<box>> || <<box>>
+<dfn>&lt;final-bg-layer></dfn> =  <<bg-image>> || <<bg-position>> [ / <<bg-size>> ]? || <<repeat-style>> || <<attachment>> || <<box>> || <<box>> || <<'background-color'>></pre>
 
 <p class=note>Note that a color is permitted in
 <<final-bg-layer>>, but not in <<bg-layer>>.