Add space to toot paragraph in landing page (#4331)

app/javascript/styles/about.scss

@@ -595,6 +595,11 @@
       line-height: inherit;
       font-weight: inherit;
       color: $primary-text-color;
+      margin-bottom: 20px;
+
+      &:last-child {
+        margin-bottom: 0;
+      }
 
       a {
         color: $ui-secondary-color;