Apply suggestions and update links to rustc book

Co-authored-by: Nathan Stocks <cleancut@github.com>

Author: Urgau

posts/2024-04-29-check-cfg.md

@@ -19,7 +19,7 @@ This is another step to our commitment to provide user-focused tooling and we ar
 
 ## A look at the feature 
 
-Every time a Cargo feature is declared that feature is transformed into a config that is passed to `rustc` (the Rust compiler) so it can verify with its [well known cfgs](TODO) if any of the `#[cfg]`, `#![cfg_attr]` and `cfg!` have unexpected configs and report a warning with the `unexpected_cfgs` lint.
+Every time a Cargo feature is declared that feature is transformed into a config that is passed to `rustc` (the Rust compiler) so it can verify with its [well known cfgs](https://doc.rust-lang.org/nightly/rustc/check-cfg.html#well-known-names-and-values) if any of the `#[cfg]`, `#![cfg_attr]` and `cfg!` have unexpected configs and report a warning with the `unexpected_cfgs` lint.
 
 *`Cargo.toml`*:
 
@@ -56,9 +56,9 @@ fn win() {}
 
 Some crates use custom cfgs that they either expected from the environment (`RUSTFLAGS`or other means) or is enabled by some logic in the crate `build.rs`. For those crates Cargo provides a new instruction: [`cargo::rustc-check-cfg`](TODO)[^2] (or `cargo:rustc-check-cfg` for older Cargo version).
 
-[^2]: `cargo::rustc-check-cfg` will start working in Rust 1.80 (or nightly-2024-04-XX), between Rust 1.77 and Rust 1.79 *(included)* it silently did nothing and before that (so Rust 1.76 and below) it warned when used without the unstable Cargo `-Zcheck-cfg`.
+[^2]: `cargo::rustc-check-cfg` will start working in Rust 1.80 (or nightly-2024-04-XX). From Rust 1.77 to Rust 1.79 *(inclusive)* it is silently ignored. In Rust 1.76 and below a warning is emitted when used without the unstable Cargo flag `-Zcheck-cfg`.
 
-The syntax to use is described in the [rustc book](https://doc.rust-lang.org/rustc/index.html) section [checking configuration](TODO), but in a nutshell the basic syntax of `--check-cfg` is:
+The syntax to use is described in the [rustc book](https://doc.rust-lang.org/nightly/rustc/) section [checking configuration](https://doc.rust-lang.org/nightly/rustc/check-cfg.html), but in a nutshell the basic syntax of `--check-cfg` is:
 
 > `cfg(name, values("value1", "value2", ..., "valueN"))`
 
@@ -89,7 +89,7 @@ fn main() {
 | `foo="1"` and `bar="2"` | `cfg(foo, values("1"))` and `cfg(bar, values("2"))` |
 | `foo` and `foo="bar"`   | `cfg(foo, values(none(), "bar"))`              |
 
-More details can be found on the [`rustc` book](TODO).
+More details can be found on the [`rustc` book](https://doc.rust-lang.org/nightly/rustc/check-cfg.html).
 
 ## Frequently asked questions
 
@@ -108,8 +108,8 @@ This means that doing `RUSTFLAGS="--cfg tokio_unstable" cargo check` will not re
 
 There is not **currently no way** to expect a custom cfg other than with `cargo::rustc-check-cfg` in a `build.rs`.
 
-Crate author that don't want to use a `build.rs` are encouraged to use Cargo features instead.
+Crate authors that don't want to use a `build.rs` are encouraged to use Cargo features instead.
 
-### Does it affect dependencies ?
+### Does the lint affect dependencies?
 
 No, the lint only affects local packages; only those will report the lint.