chore: fix typo in comment (#5643)

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protocols/kad/src/query/peers/fixed.rs

@@ -25,7 +25,7 @@ use std::{collections::hash_map::Entry, num::NonZeroUsize, vec};
 
 /// A peer iterator for a fixed set of peers.
 pub(crate) struct FixedPeersIter {
-    /// Ther permitted parallelism, i.e. number of pending results.
+    /// The permitted parallelism, i.e. number of pending results.
     parallelism: NonZeroUsize,
 
     /// The state of peers emitted by the iterator.