Markdown.pl: keep valid tag list alphabetized

While trying to keep all the various table-related tags together
is admirable, it makes it hard to be sure the tag is in the list
or not (an also looks bad compared to the other tags).

Therefore put the table-related tags into alphabetical order
just like the rest of them.

Signed-off-by: Kyle J. McKay <mackyle@gmail.com>

Markdown.pl

@@ -1838,7 +1838,7 @@ BEGIN {
     %ok_tag_name = map({$_ => 1} qw(
 	a abbr acronym address
 	b basefont bdo big blockquote br
-	caption center cite code
+	caption center cite code col colgroup
 	dd del dfn dir div dl dt
 	em
 	font
@@ -1851,7 +1851,7 @@ BEGIN {
 	p pre
 	q
 	s samp small span strike strong sub sup
-	table tbody thead tfoot col colgroup tr th td tt
+	table tbody td tfoot th thead tr tt
 	u ul
 	var
     ));