x/website: Documentation supports code highlighting

[SherlockGy]

What is the URL of the page with the issue?

https://go.dev/doc/tutorial/database-access
https://go.dev/doc/effective_go
etc.

What did you expect to see?

code highlighting for Docs and Tutorials

[mvdan]

Also #40952 and #52198. I think we should have a single umbrella issue for all of these.

[SherlockGy]

The Go Playground and the website front page are also need code highlighting

[hyangah]

Closing. Let's centralize the discussion in the umbrella issue.