docs: fix backporting error in attributes (#2780)

There was an error when backporting #1378 (here: #1418) and a trailing
dot (.) was forgotten (which was breaking the link). Fixed also the link to
`std::fmt::Debug`.

tracing-attributes/src/lib.rs

@@ -94,11 +94,13 @@ mod expand;
 /// By default, all arguments to the function are included as fields on the
 /// span. Arguments that are `tracing` [primitive types] implementing the
 /// [`Value` trait] will be recorded as fields of that type. Types which do
-/// not implement `Value` will be recorded using [`std::fmt::Debug`].
+/// not implement `Value` will be recorded using [`fmt::Debug`].
 ///
 /// [primitive types]: https://docs.rs/tracing/latest/tracing/field/trait.Value.html#foreign-impls
 /// [`Value` trait]: https://docs.rs/tracing/latest/tracing/field/trait.Value.html
 ///
+/// # Overriding Span Attributes
+///
 /// To skip recording a function's or method's argument, pass the argument's name
 /// to the `skip` argument on the `#[instrument]` macro. For example,
 /// `skip` can be used when an argument to an instrumented function does
@@ -164,7 +166,6 @@ mod expand;
 ///     // ...
 /// }
 /// ```
-/// ```
 /// # use tracing_attributes::instrument;
 /// // A struct which owns a span handle.
 /// struct MyStruct