Redirect for prototype/ -> unstable/

[H-Huang]

🚀 Describe the improvement or the new tutorial

When I search "flight recorder pytorch" on Google

The top link is https://docs.pytorch.org/tutorials/prototype/flight_recorder_tutorial.html

whereas now these tutorials are under https://docs.pytorch.org/tutorials/unstable/flight_recorder_tutorial.html

Can we add a redirect? I knew that the tutorial should be there since i actively work on PyTorch, but for new users this will be confusing and also when prototype/ is in URL path, the site doesn't have any CSS and is scary-looking

Existing tutorials on this topic

No response

Additional context

No response

[H-Huang]

cc @svekars @sekyondaMeta

[AlannaBurke]

@sekyondaMeta aside from fixing the redirect, is there a reason that 404 page is so ugly?