Add responsive gutter example (4 integers)

Author: agriyakhetarpal

layouts/shortcodes/grid.html

@@ -154,6 +154,24 @@
 
 {{< /grid >}}
 
+Here's a grid with responsive gutters (i.e., "xs sm md lg" are set).
+
+{{< grid columns="1 2 2 3" gutter="1 1 3 4" >}}
+
+[[item]]
+type = 'card'
+body = 'Responsive gutter: 0.25rem on mobile, 1rem on tablet, 1.5rem on desktop'
+
+[[item]]
+type = 'card'
+body = 'Responsive gutter: 0.25rem on mobile, 1rem on tablet, 1.5rem on desktop'
+
+[[item]]
+type = 'card'
+body = 'Responsive gutter: 0.25rem on mobile, 1rem on tablet, 1.5rem on desktop'
+
+{{< /grid >}}
+
 */}}
 
 {{- $items := "" -}}