Improve the instructions on how to build the docs (#56018)
Summary:
This PR includes:
- A formatting change to make katex installation instructions more visible for Facebook employees.
- A short tip about how to start a lightweight HTTP server on a remote machine to browse the doc build artifacts.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/56018
Reviewed By: H-Huang
Differential Revision: D27765157
Pulled By: cbalioglu
fbshipit-source-id: 67663de0ba7b742e0deb5358d1e45eea9edd840f
