Fix some typos (#4565)

validator_client/src/duties_service.rs

@@ -1021,7 +1021,7 @@ async fn fill_in_selection_proofs<T: SlotClock + 'static, E: EthSpec>(
 /// 2. We won't miss a block if the duties for the current slot happen to change with this poll.
 ///
 /// This sounds great, but is it safe? Firstly, the additional notification will only contain block
-/// producers that were not included in the first notification. This should be safety enough.
+/// producers that were not included in the first notification. This should be safe enough.
 /// However, we also have the slashing protection as a second line of defence. These two factors
 /// provide an acceptable level of safety.
 ///

validator_client/src/lib.rs

@@ -524,7 +524,7 @@ impl<T: EthSpec> ProductionValidatorClient<T> {
 
     pub fn start_service(&mut self) -> Result<(), String> {
         // We use `SLOTS_PER_EPOCH` as the capacity of the block notification channel, because
-        // we don't except notifications to be delayed by more than a single slot, let alone a
+        // we don't expect notifications to be delayed by more than a single slot, let alone a
         // whole epoch!
         let channel_capacity = T::slots_per_epoch() as usize;
         let (block_service_tx, block_service_rx) = mpsc::channel(channel_capacity);