feat(PWA): add Service Worker update notification

_sass/addon/commons.scss

@@ -1150,6 +1150,51 @@ $sidebar-display: "sidebar-display";
   -webkit-transform: translate3d(0, -5px, 0);
 }
 
+#notification {
+  @keyframes popup {
+    from {
+      opacity: 0;
+      bottom: 0;
+    }
+  }
+
+  .toast-header {
+    background: none;
+    border-bottom: none;
+    color: inherit;
+  }
+
+  .toast-body {
+    font-family: 'Lato';
+    line-height: 1.25rem;
+
+    button {
+      font-size: 90%;
+      min-width: 4rem;
+    }
+  }
+
+  &.toast {
+    display: none;
+
+    &.show {
+      display: block;
+      min-width: 20rem;
+      border-radius: 0.5rem;
+      -webkit-backdrop-filter: blur(10px);
+      backdrop-filter: blur(10px);
+      background-color: rgba(255, 255, 255, 0.5);
+      color: #1b1b1eba;
+      position: fixed;
+      left: 50%;
+      bottom: 20%;
+      transform: translateX(-50%);
+      animation: popup 0.8s;
+    }
+  }
+
+}
+
 /*
   Responsive Design: