refactor events and errors pallet-distance

pallets/distance/src/lib.rs

@@ -165,15 +165,21 @@ pub mod pallet {
 
     #[pallet::error]
     pub enum Error<T> {
+        /// Distance already in evaluation for caller.
         AlreadyInEvaluation,
-        CannotReserve,
+        /// Too many evaluation requests for this author.
         ManyEvaluationsByAuthor,
+        /// Too many evaluations for this block.
         ManyEvaluationsInBlock,
+        /// No author for this block.
         NoAuthor,
+        /// Caller has no identity.
         NoIdentity,
-        NonEligibleForEvaluation,
+        /// Evaluation queue is full.
         QueueFull,
+        /// Too many evaluators in the current evaluation pool.
         TooManyEvaluators,
+        /// Evaluation result has a wrong length.
         WrongResultLength,
     }