Fix OSS rustdoc warnings breaking the Linux CI job

Summary:
The OSS `facebook/buck2` `linux-build-and-test` CI job has been red because `test.py`'s rustdoc stage runs `cargo doc --message-format=json --no-deps` and exits 1 on any documentation warning. Six warnings had accumulated. This fixes all four sites:

- `app/buck2_client_ctx/src/subscribers/superconsole.rs`: `rustdoc::invalid_html_tags` fired twice, reporting unclosed HTML tags "trace" and "argv", because the doc comment wrote the angle-bracketed placeholders as bare angle brackets, which rustdoc parses as HTML. Wrapped the phrase in backticks so it becomes inline code.

- `starlark-rust/starlark/src/values/types/enumeration.rs`: `rustdoc::broken_intra_doc_links` fired twice on a link to `EnumType`. No such public item exists — the module exports `pub(crate) use enum_type::AnyEnumType` and `pub use value::EnumValue`, and `enum_type.rs` declares only `pub(crate) struct EnumTypeGen`. Replaced the links with prose.

- `starlark-rust/starlark/src/values/alloc_value.rs`: `Heap::alloc_complex` does not exist; the real methods are `alloc_complex_no_freeze` and `alloc_complex_branded`. Pointed the link at `alloc_complex_no_freeze`.

- `starlark-rust/starlark/src/eval/runtime/params/spec.rs`: `rustdoc::private_intra_doc_links` fired because public documentation linked to `ParametersSpec::as_value`, which is `pub(crate) fn as_value`. Demoted the link to plain code formatting.

Note that `test.py` silently discards any rustdoc warning whose target `src_path` does not contain the substring `/buck2/`, so reproducing this locally requires checking the repo out into a path containing `/buck2/`.

Reviewed By: NavidQar

Differential Revision: D116114053

fbshipit-source-id: 4c9bda31589aca6fdb046d32889eca1a11a64911

Author: 8Keep

starlark/src/eval/runtime/params/spec.rs

@@ -163,7 +163,7 @@ pub struct ParametersSpec<V> {
 }
 
 /// `Frozen` ignores the brand: the frozen spec keeps its defaults as `FrozenValue`, because
-/// [`ParametersSpec::as_value`] reads the frozen and the unfrozen spec through one type, at the
+/// `ParametersSpec::as_value` reads the frozen and the unfrozen spec through one type, at the
 /// reader's lifetime. Branding the defaults waits for `FrozenValue` to be branded.
 impl<'v> FreezeBranded for ParametersSpec<Value<'v>> {
     type Frozen<'fv> = ParametersSpec<FrozenValue>;

starlark/src/values/alloc_value.rs

@@ -35,7 +35,7 @@ use crate::values::type_repr::StarlarkTypeRepr;
 /// is implemented for `char` to construct Starlark `str`.
 ///
 /// For types that implement [`crate::values::StarlarkValue`] a typical implementation
-/// will probably call either [`Heap::alloc_simple`] or [`Heap::alloc_complex`],
+/// will probably call either [`Heap::alloc_simple`] or [`Heap::alloc_complex_no_freeze`],
 /// e.g.
 ///
 /// ```

starlark/src/values/types/enumeration.rs

@@ -17,7 +17,7 @@
 
 //! Fixed set enumerations, with runtime checking of validity.
 //!
-//! Calling `enum()` produces an [`EnumType`]. Calling the [`EnumType`] creates an [`EnumValue`].
+//! Calling `enum()` produces an enum type. Calling that enum type creates an [`EnumValue`].
 //!
 //! The implementation ensures that each value of the enumeration is only stored once,
 //! so they may also provide (modest) memory savings. Created in starlark with the