change working group overview page to 2 column

Signed-off-by: Toshaan Bharvani <toshaan@vantosh.com>

themes/openpowerfoundation/layouts/groups/list.html

@@ -23,7 +23,7 @@
 		{{ $imagename := .Param "image" }}
 		{{ $imagelocation := (printf "%s/%s" "images/groups/" $imagename) }}
 		{{ $imageresource := resources.Get $imagelocation }}
-		<article class="post__article col-md-4">
+		<article class="post__article col-md-6">
 			{{ if $imageresource }}
 			<div class="post__thumb">
 				{{ $image := $imageresource.Fit "390x390 webp" }}