Improve SEO #302

Description

If you google "git basics dzcode.io", you will see old URLs like:
https://www.dzcode.io/Learn/Git_Basics/Git_and_Github
which doesn't exists anymore, but because the website is a single page application, google thinks that this is a valid page.

One more problem is, when you go to:
https://developers.google.com/speed/pagespeed/insights/?url=www.dzcode.io
you will see that the score is not good, especially in mobile.

This task will improve the overall SEO rank of dzcode.io website.

Check List

• Setup a Proper redirects: fix: Cloudflare 404 redirect #603
• Apply suggesstion from Google pagespeed insights fix: Apply lighthouse tips #602
• Add robot.txt to disallow indexing non production version of the website #473 and fix: robots.txt #601
• Bug: Google bot isn't able to fetch data from api.dzcode.io #478
• Perf: Improve initial page load experience #306
• send Lighthouse analytics to grafana
• Fix: set canonical url #631
• report web vitals