style: add vertical spacing between feature cards on homepage

Added row-gap: 2rem to create better visual separation between feature card rows

Author: speier

website/src/pages/index.module.css

@@ -109,6 +109,10 @@
   background: var(--ifm-background-color);
 }
 
+.features .row {
+  row-gap: 2rem;
+}
+
 .feature {
   padding: 2rem;
   height: 100%;