Add tracing-actix-web

[LukeMathWalker]

Adding a mention to tracing-actix-web in the ecosystem section.

[hawkw]

Thanks! There's also a list of related crates in the tracing crate's RustDoc --- can you add it there, as well?

tracing/tracing/src/lib.rs

Lines 752 to 783 in 6ade36d

	//! Additionally, there are also several third-party crates which are not
	//! maintained by the `tokio` project. These include:
	//!
	//! - [`tracing-timing`] implements inter-event timing metrics on top of `tracing`.
	//! It provides a subscriber that records the time elapsed between pairs of
	//! `tracing` events and generates histograms.
	//! - [`tracing-opentelemetry`] provides a subscriber for emitting traces to
	//! [OpenTelemetry]-compatible distributed tracing systems.
	//! - [`tracing-honeycomb`] Provides a layer that reports traces spanning multiple machines to [honeycomb.io]. Backed by [`tracing-distributed`].
	//! - [`tracing-distributed`] Provides a generic implementation of a layer that reports traces spanning multiple machines to some backend.
	//! - [`tracing-actix`] provides `tracing` integration for the `actix` actor
	//! framework.
	//! - [`tracing-gelf`] implements a subscriber for exporting traces in Greylog
	//! GELF format.
	//! - [`tracing-coz`] provides integration with the [coz] causal profiler
	//! (Linux-only).
	//! - [`tracing-bunyan-formatter`] provides a layer implementation that reports events and spans
	//! in [bunyan] format, enriched with timing information.
	//! - [`tracing-wasm`] provides a `Collect`/`Subscribe` implementation that reports
	//! events and spans via browser `console.log` and [User Timing API (`window.performance`)].
	//! - [`tide-tracing`] provides a [tide] middleware to trace all incoming requests and responses.
	//! - [`test-env-log`] takes care of initializing `tracing` for tests, based on
	//! environment variables with an `env_logger` compatible syntax.
	//! - [`tracing-unwrap`] provides convenience methods to report failed unwraps
	//! on `Result` or `Option` types to a [`collect`].
	//! - [`diesel-tracing`] provides integration with [`diesel`] database connections.
	//! - [`tracing-tracy`] provides a way to collect [Tracy] profiles in instrumented
	//! applications.
	//! - [`tracing-elastic-apm`] provides a layer for reporting traces to [Elastic APM].
	//!
	//! If you're the maintainer of a `tracing` ecosystem crate not listed above,
	//! please let us know! We'd love to add your project to the list!

[LukeMathWalker]

I had completely forgot about this PR 😅
Fixed both docs and rebased ✅