[docs] Links are missing a trailing slash in server rendered pages

[oliviertassinari]

Steps to reproduce

#3301 (comment)

[Janpot]

I know we've discussed it before, but I can you remind me again why we use trailingSlash?

For my future self I'd like to add a documentation comment about it in the configuration. Having worked a lot on this in the next.js codebase, it feels a bit to me like a neglected feature and I'd expect it to regress regularly. Personally I can't think of a technical limitation that mandates this.

[oliviertassinari]

I can you remind me again why we use trailingSlash?

It's a historical decision. Changing this would mean we need redirect all the URLs. We could use the move of all the docs to subdomains as an opportunity to change it (batching).

[oliviertassinari]

Ok, origin found: mui/material-ui#16705. We started to use trailingSlash precisely to avoid introducing changes to the URLs.

Points added to https://www.notion.so/mui-org/docs-infra-Change-docs-domain-0ce329e7ebc34aba8fbf4f3c5e13eb5d?pvs=4#275627e520784cf4b77733f7805465d9 so we don't forget about this.