Ability to use code snippet from GitHub

[ydcjeff]

Clear and concise description of the problem

Having to include base64 urls in the docs makes the docs unable to scan.

Suggested solution

• Fetch the code snippets/examples from GitHub and show them in the code editor pane.
• URL can be like <netlify-subdomain>/?github/<username or org>/repo/tree/dir/main.py.
• Use fetch to get content from GitHub raw url.
• Replace the original url with the url stated above.

Alternative

Make use of GitHub Authentication.

Additional context

N/A