Fix documentation for wasm32-unknown-unknown

[o01eg]

Fixes #76526 (comment)

[rust-highfive]

r? @Mark-Simulacrum

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[Mark-Simulacrum]

@bors r+

[bors]

📌 Commit 26781c3 has been approved by Mark-Simulacrum

[Dylan-DPC]

failed in rollup

@bors r-

[o01eg]

On Windows it gives:

error: unresolved link to `AsFd::as_fd`
  --> library\std\src\os\fd\raw.rs:35:60
   |
35 |     /// However, borrowing is not strictly required. See [`AsFd::as_fd`]
   |                                                            ^^^^^^^^^^^ no item named `AsFd` in scope
   |
   = note: `-D rustdoc::broken-intra-doc-links` implied by `-D warnings`

Maybe I should somehow rephrase it because without it I get:

error[E0432]: unresolved import `crate::os::unix::io`
 --> library/std/src/os/fd/raw.rs:9:22
  |
9 | use crate::os::unix::io::AsFd;
  |                      ^^ could not find `io` in `unix`

[o01eg]

I've tried to fix it and rebased PR.

[Dylan-DPC]

@bors r=Mark-Simulacrum

[bors]

📌 Commit 3f4bbd5 has been approved by Mark-Simulacrum