Fix checklist in markdown

* Add strip-markdown
* Add CopyButton component
* Fix copy code
* Add about page
* Use async function with get all markdown content
* Add shortcut icon
* Remove useless code

components/post/CopyButton.tsx

@@ -0,0 +1,39 @@
+import { Button, useClipboard } from '@chakra-ui/react';
+import { FC, MouseEventHandler, useEffect, useState } from 'react';
+
+const CopyButton: FC = ({ children }) => {
+  // Copy code
+  const [codeContent, setCodeContent] = useState('');
+  const { hasCopied, onCopy } = useClipboard(codeContent);
+
+  const copyCode: MouseEventHandler<HTMLButtonElement> = (e) => {
+    const target = e.target as HTMLButtonElement;
+    // Button is sibling with Code tag
+    const codeToCopy = target.nextElementSibling?.textContent;
+    codeToCopy && setCodeContent(codeToCopy);
+  };
+  useEffect(() => {
+    codeContent && onCopy();
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [codeContent]);
+
+  return (
+    <>
+      <pre>
+        <Button
+          size="xs"
+          colorScheme="teal"
+          position="absolute"
+          top="5px"
+          right="5px"
+          onClick={copyCode}
+        >
+          {hasCopied ? 'COPYIED' : 'COPY'}
+        </Button>
+        {children}
+      </pre>
+    </>
+  );
+};
+
+export default CopyButton;