feat(shortcode): add mapbox shortcode (#190)

* feat(shortcode): add mapbox shortcode

* docs: split shortcodes into built-in shortcodes and extended shortcodes

* docs(shortcodes): add docs for mapbox shortcode

* docs(shortcodes): fix an error in shortcodes docs

assets/css/_page/_single.scss

@@ -34,7 +34,7 @@
   }
 
   .featured-image {
-    padding-top: .6rem;
+    margin: .5rem 0;
 
     img {
       display: block;
@@ -91,8 +91,14 @@
       .dark-theme & {
         font-weight: bolder;
       }
+    }
 
-      & > .header-mark::before {
+    > h2,
+    > h3,
+    > h4,
+    > h5,
+    > h6 {
+      > .header-mark::before {
         content: "|";
         margin-right: .3125rem;
         color: $single-link-color;
@@ -103,12 +109,11 @@
       }
     }
 
-    h2 > .header-mark::before {
+    > h2 > .header-mark::before {
       content: "#";
     }
 
     p {
-      font-size: 1rem;
       margin: .5rem 0;
     }
 
@@ -136,6 +141,7 @@
     }
 
     ul {
+      margin: .5rem 0;
       padding-left: 2rem;
       list-style-type: disc;
     }
@@ -278,12 +284,18 @@
       .dark-theme & {
         color: $global-font-secondary-color-dark;
       }
+
+      p {
+        margin: .25rem 0;
+      }
     }
 
     @import "../_partial/_single/code";
     @import "../_partial/_single/instagram";
     @import "../_partial/_single/admonition";
     @import "../_partial/_single/echarts";
+    @import "../_partial/_single/mapbox";
+    @import "../_partial/_single/music";
     @import "../_partial/_single/bilibili";
 
     hr {