[selectors] Move column combinator to Selectors 5

Author: cdoublev

selectors-4/Overview.bs

@@ -4471,7 +4471,7 @@ Grammar</h2>
 	<dfn>&lt;simple-selector></dfn> = <<type-selector>> | <<subclass-selector>>
 
 
-	<dfn>&lt;combinator></dfn> = '>' | '+' | '~' | [ '|' '|' ]
+	<dfn>&lt;combinator></dfn> = '>' | '+' | '~'
 
 	<dfn noexport>&lt;wq-name></dfn> = <<ns-prefix>>? <<ident-token>>
 	<dfn noexport>&lt;ns-prefix></dfn> = [ <<ident-token>> | '*' ]? '|'
@@ -4516,7 +4516,6 @@ Grammar</h2>
 		* Between the components of an <<attr-matcher>>.
 		* Between the <<compound-selector>> or <<pseudo-compound-selector>>s
 			in a <<complex-selector-unit>>
-		* Between the components of a <<combinator>>.
 
 		Whitespace is <em>required</em>
 		between two <<complex-selector-unit>>s

selectors-5/Overview.bs

@@ -475,6 +475,22 @@ Reference combinators <code>/ref/</code></h3>
 	</div>
 
 
+<h2 id="grammar" oldids="formal-syntax">
+Grammar</h2>
+
+	This module extends the CSS grammar of selectors with:
+
+	<pre class=prod>
+	<dfn>&lt;combinator></dfn> = '>' | '+' | '~' | [ '|' '|' ] | [ / <<wq-name>> / ]
+	</pr>
+
+	<ul>
+	<li id="white-space">
+		White space is forbidden:
+		* Between the components of a <<combinator>>.
+	</ul>
+
+
 <h2 id="changes">
 Changes</h2>