Redesign the post meta layout

- posted date
- updated date
- read time
- license statement of post bottom
- also refactor the `timeago.js`

_sass/addon/module.scss

@@ -63,6 +63,10 @@
   cursor: pointer;
 }
 
+%normal-font-style {
+  font-style: normal;
+}
+
 /* ---------- scss mixin --------- */
 
 @mixin no-text-decoration {
@@ -88,10 +92,6 @@
   opacity: 0.6;
 }
 
-@mixin semi-bold {
-  font-weight: 600;
-}
-
 @mixin label($font-size: 1rem, $font-weight: 600, $color: var(--label-color)) {
   color: $color;
   font-size: $font-size;