docs(topic): Raise visibility of error tutorial

src/_topic/error.rs

@@ -1,13 +1,27 @@
 //! # Custom Errors
 //!
-//! The most basic error type is [`ParserError`][crate::error::ParserError]
+//! Between [`ContextError`], [`Parser::context`], and [`cut_err`],
+//! most error needs will likely be met
+//! (see [tutorial][chapter_6]).
+//! When that isn't the case, you can implement your own error type.
+//!
+//! The most basic error trait is [`ParserError`].
 //!
 //! Optional traits include:
-//! - [`AddContext`][crate::error::AddContext]
-//! - [`FromExternalError`][crate::error::FromExternalError]
+//! - [`AddContext`]
+//! - [`FromExternalError`]
 //!
 //! # Example
 //!
 //!```rust
 #![doc = include_str!("../../examples/custom_error.rs")]
 //!```
+
+#![allow(unused_imports)]
+use crate::combinator::cut_err;
+use crate::error::ContextError;
+use crate::Parser;
+use crate::_tutorial::chapter_6;
+use crate::error::AddContext;
+use crate::error::FromExternalError;
+use crate::error::ParserError;