error: add note about introspection

Author: BurntSushi

CHANGELOG.md

@@ -9,6 +9,8 @@ Enhancements:
 * [#412](https://github.com/BurntSushi/jiff/issues/412):
 Add `Display`, `FromStr`, `Serialize` and `Deserialize` trait implementations
 for `jiff::civil::ISOWeekDate`. These all use the ISO 8601 week date format.
+* [#418](https://github.com/BurntSushi/jiff/issues/418):
+Add some basic predicates to `jiff::Error` for basic error introspection.
 
 
 0.2.16 (2025-11-07)

src/error/mod.rs

@@ -27,8 +27,11 @@ pub(crate) mod zoned;
 ///
 /// Other than implementing the [`std::error::Error`] trait when the
 /// `std` feature is enabled, the [`core::fmt::Debug`] trait and the
-/// [`core::fmt::Display`] trait, this error type currently provides no
-/// introspection capabilities.
+/// [`core::fmt::Display`] trait, this error type currently provides
+/// very limited introspection capabilities. Simple predicates like
+/// `Error::is_range` are provided, but the predicates are not
+/// exhaustive. That is, there exist some errors that do not return
+/// `true` for any of the `Error::is_*` predicates.
 ///
 /// # Design
 ///