doc: enable doc_cfg

src/catch/gradual_difficulty.rs

@@ -47,6 +47,7 @@ use super::{
 ///     // ...
 /// }
 /// ```
+#[cfg_attr(docsrs, doc(cfg(feature = "gradual")))]
 #[derive(Clone, Debug)]
 pub struct CatchGradualDifficulty<'map> {
     pub(crate) idx: usize,

src/catch/gradual_performance.rs

@@ -92,6 +92,7 @@ use super::{CatchGradualDifficulty, CatchPerformanceAttributes, CatchScoreState}
 /// // attempting to process further objects will return `None`.
 /// assert!(gradual_perf.next(state).is_none());
 /// ```
+#[cfg_attr(docsrs, doc(cfg(feature = "gradual")))]
 #[derive(Clone, Debug)]
 pub struct CatchGradualPerformance<'map> {
     difficulty: CatchGradualDifficulty<'map>,