feat(code): add copy button for code (#239)

assets/lib/VERSION

@@ -6,9 +6,10 @@ smooth-scroll@16.1.2 https://github.com/cferdinandi/smooth-scroll
 autocomplete.js@0.37.1 https://github.com/algolia/autocomplete.js
 lunr.js@2.3.8 https://lunrjs.com/
 algoliasearch@4.1.0 https://github.com/algolia/algoliasearch-client-javascript
-sharer@0.4.0 https://github.com/ellisonleao/sharer.js
 lazysizes@5.2.0 https://github.com/aFarkas/lazysizes
 lightgallery.js@1.1.3 lg-thumbnail@1.1.0 lg-zoom@1.1.0 https://github.com/sachinchoolur/lightgallery.js
+clipboard.js@2.0.6 https://github.com/zenorocha/clipboard.js
+sharer@0.4.0 https://github.com/ellisonleao/sharer.js
 typeit@6.5.1 https://github.com/alexmacarthur/typeit
 katex@0.11.1 https://katex.org/
 mermaid@8.4.8 https://github.com/knsv/mermaid

assets/lib/polyfill.yml

@@ -10,3 +10,4 @@ theme:
   - Object.values
   - Promise
   - fetch
+  - Element.prototype.after