rust: pci: fix docs related to missing Markdown code spans

In particular:

  - Add missing Markdown code spans.

  - Improve title for `DeviceId`, adding a link to the struct in the
    C side, rather than referring to `bindings::`.

  - Convert `TODO` from documentation to a normal comment, and put code
    in block.

This was found using the Clippy `doc_markdown` lint, which we may want
to enable.

Fixes: 1bd8b6b ("rust: pci: add basic PCI device / driver abstractions")
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20250324210359.1199574-8-ojeda@kernel.org
[ Prefixed link text with `struct`. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Author: ojeda

rust/kernel/pci.rs

@@ -118,7 +118,9 @@ macro_rules! module_pci_driver {
 };
 }
 
-/// Abstraction for bindings::pci_device_id.
+/// Abstraction for the PCI device ID structure ([`struct pci_device_id`]).
+///
+/// [`struct pci_device_id`]: https://docs.kernel.org/PCI/pci.html#c.pci_device_id
 #[repr(transparent)]
 #[derive(Clone, Copy)]
 pub struct DeviceId(bindings::pci_device_id);
@@ -173,7 +175,7 @@ unsafe impl RawDeviceId for DeviceId {
     }
 }
 
-/// IdTable type for PCI
+/// `IdTable` type for PCI.
 pub type IdTable<T> = &'static dyn kernel::device_id::IdTable<DeviceId, T>;
 
 /// Create a PCI `IdTable` with its alias for modpost.
@@ -224,10 +226,11 @@ macro_rules! pci_device_table {
 /// `Adapter` documentation for an example.
 pub trait Driver: Send {
     /// The type holding information about each device id supported by the driver.
-    ///
-    /// TODO: Use associated_type_defaults once stabilized:
-    ///
-    /// type IdInfo: 'static = ();
+    // TODO: Use `associated_type_defaults` once stabilized:
+    //
+    // ```
+    // type IdInfo: 'static = ();
+    // ```
     type IdInfo: 'static;
 
     /// The table of device ids supported by the driver.