Use flex column direction to put footer at bottom

app/assets/javascripts/vue_shared/new_namespace/components/welcome.vue

@@ -30,7 +30,7 @@ export default {
 };
 </script>
 <template>
-  <div class="container">
+  <div class="container gl-display-flex gl-flex-direction-column">
     <h2 class="gl-my-7 gl-font-size-h1 gl-text-center">
       {{ title }}
     </h2>