[wwwdocs] Revamp formatting markup of bugs/management.html

[Gerald Pfeifer]

On Sun, 2 Sep 2018, Gerald Pfeifer wrote:
> ...making this page HTML 5 compliant.

And with this little follow-up this page solely uses CSS, removing
a sole warning the validator still showed after my change last week.

Applied.

Gerald

Index: bugs/management.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/bugs/management.html,v
retrieving revision 1.39
diff -u -r1.39 management.html
--- bugs/management.html	2 Sep 2018 17:30:48 -0000	1.39
+++ bugs/management.html	9 Sep 2018 22:00:53 -0000
@@ -86,7 +86,7 @@
 <p>The following two fields describe how serious a bug is from a user's
 perspective (Severity) and what Priority we assign to it in fixing it:</p>
 
-<table class="padding5" border="1"><tr>
+<table class="border padding5"><tr>
 <td class="top">
 
 <h3 class="center" id="severity">Severity</h3>