Add salvo to HTTP Server see_also

[AuroraMaster]

Adds salvo to the HTTP Server section under see_also.

Why

salvo is an actively maintained hyper/tokio-based web framework (~4.3k stars, last push within the week). It already shows up alongside axum/actix/rocket/poem/warp on the other major Rust web discovery lists — awesome-rust and Are We Web Yet? — and has an entry in TechEmpower FrameworkBenchmarks. blessed.rs appears to be the only one of the established discovery resources that doesn't list it.

Where it fits

It belongs in see_also rather than recommendations: axum/actix-web are the right defaults; salvo is the right pointer for users who want simpler handler signatures (no complex generic bounds), and who want OpenAPI generation and TLS/ACME built into the framework rather than wired up separately.

I kept the note one line, matching the style of the other entries.

[djc]

Recent downloads:

• axum: 75M
• actix-web: 9.3M
• rocket: 1.1M
• poem: 780k
• warp: 4.6M
• tide: 316k
• salvo: 1.7M

As such, I think adding salvo makes sense. I suggest the following:

• One commit that removes poem and tide for being too unpopular
• One commit that re-orders see also in order of descending recent downloads (so warp, rocket)
• One commit that adds salvo between warp and rocket

[AuroraMaster]

Thanks! Pushed (2) and (3) as separate commits — see_also is now reordered descending by recent downloads, with salvo between warp and rocket.

I left (1) (removing poem/tide) out — as the author of this PR adding salvo, it doesn't feel like my call to make. Leaving that to the maintainers.