Add log feature, document features

Author: wooorm

Cargo.toml

@@ -20,6 +20,7 @@ harness = false
 [features]
 default = []
 json = ["dep:serde", "dep:serde_json"]
+log = ["dep:log"]
 
 [dependencies]
 log = { version = "0.4", optional = true }

examples/lib.rs

@@ -1,6 +1,6 @@
 fn main() -> Result<(), String> {
     // Turn on debugging.
-    // You can show it with `RUST_LOG=debug cargo run --example lib`
+    // You can show it with `RUST_LOG=debug cargo run --features log --example lib`
     env_logger::init();
 
     // Safely turn (untrusted?) markdown into HTML.

readme.md

@@ -247,7 +247,7 @@ The following bash scripts are useful when working on this project:
     ```
 *   run examples:
     ```sh
-    RUST_BACKTRACE=1 RUST_LOG=debug cargo run --example lib
+    RUST_BACKTRACE=1 RUST_LOG=debug cargo run --features log --example lib
     ```
 *   format:
     ```sh

src/lib.rs

@@ -11,6 +11,17 @@
 //!     constructs (GFM, MDX, and the like)
 //! *   [`to_mdast()`][]
 //!     — turn markdown into a syntax tree
+//!
+//! ## Features
+//!
+//! *   **`default`**
+//!     — nothing is enabled by default
+//! *   **`json`**
+//!     — enable serde to serialize the AST (includes `dep:serde`, `dep:serde_json`)
+//! *   **`log`**
+//!     — enable logging (includes `dep:log`);
+//!     you can show logs with `RUST_LOG=debug`
+
 #![no_std]
 #![deny(clippy::pedantic)]
 #![allow(clippy::doc_link_with_quotes)]