fix mdx files

Author: silkie-chicken

content/posts/rich-content-with-mdx.mdx

@@ -12,8 +12,6 @@ MDX supports to import React component and embed it directly as markdown content
 
 ## Instagram with react-instagram-embed
 
-import InstagramEmbed from "react-instagram-embed";
-
 <p>
   <InstagramEmbed
     url="https://instagr.am/p/Zw9o4/"
@@ -24,16 +22,12 @@ import InstagramEmbed from "react-instagram-embed";
 
 ## YouTube with react-youtube
 
-import YouTube from "react-youtube";
-
 <p>
   <YouTube videoId={"2g811Eo7K8U"} containerClassName={"youtube-container"} />
 </p>
 
 ## Twitter with react-twitter-embed
 
-import { TwitterTweetEmbed } from "react-twitter-embed";
-
 <p>
   <TwitterTweetEmbed tweetId={"933354946111705097"} />
 </p>