add lookahead epochs (#7)

* update to mention lookahead epochs

* clarify current and lookahead epochs

* review comments

apis/validator/beacon_committee_selections.yaml

@@ -5,9 +5,10 @@ post:
     This endpoint should be used by a validator client running as part of a distributed validator cluster, and is 
     implemented by a distributed validator middleware client. This endpoint is used to exchange partial 
     selection proofs for combined/aggregated selection proofs to allow a validator client 
-    to correctly determine if one of its validators has been selected to perform an aggregation duty in a slot. 
-    Validator clients must query this endpoint at the start of an epoch for all validators that have attester duties 
-    in that epoch. Consensus clients need not support this endpoint and may return a 501.
+    to correctly determine if any of its validators has been selected to perform an attestation aggregation duty in a slot. 
+    Validator clients must query this endpoint at the start of an epoch for the current and lookahead (next) epochs for
+    all validators that have attester duties in the current and lookahead epochs. Consensus clients need not support this
+    endpoint and may return a 501.
   tags:
     - Validator
   requestBody:

apis/validator/sync_committee_selections.yaml

@@ -5,11 +5,11 @@ post:
     Submit sync committee selections to a DVT middleware client. It returns the threshold aggregated sync 
     committee selection. This endpoint should be used by a validator client running as part of a distributed 
     validator cluster, and is implemented by a distributed validator middleware client. This endpoint is 
-    used to exchange partial selection proof slot signatures for combined/aggregated selection proofs to 
-    allow a validator client to correctly determine if one of its validators has been selected to perform a 
+    used to exchange partial selection proofs (slot signatures) for combined/aggregated selection proofs to 
+    allow a validator client to correctly determine if any of its validators has been selected to perform a 
     sync committee contribution (sync aggregation) duty in a slot. Validator clients must query this endpoint
-    at the start of an epoch for all validators that have sync committee contribution duties in that epoch. 
-    Consensus clients need not support this endpoint and may return a 501.
+    at the start of each slot for all validators that are included in the current sync committee. Consensus
+    clients need not support this endpoint and may return a 501.
   tags:
     - Validator
   requestBody: