Merge pull request #3154 from dapplion/blobs-byroot-errorcode

Clarify BeaconBlockAndBlobsSidecarByRoot no blob available

specs/eip4844/p2p-interface.md

@@ -186,7 +186,7 @@ No more than `MAX_REQUEST_BLOCKS` may be requested at a time.
 The response MUST consist of zero or more `response_chunk`.
 Each _successful_ `response_chunk` MUST contain a single `SignedBeaconBlockAndBlobsSidecar` payload.
 
-Clients MUST support requesting blocks and sidecars since the latest finalized epoch.
+Clients MUST support requesting blocks and sidecars since `minimum_request_epoch`, where `minimum_request_epoch = max(finalized_epoch, current_epoch - MIN_EPOCHS_FOR_BLOBS_SIDECARS_REQUESTS, EIP4844_FORK_EPOCH)`. If any root in the request content references a block earlier than `minimum_request_epoch`, peers SHOULD respond with error code `3: ResourceUnavailable`.
 
 Clients MUST respond with at least one block and sidecar, if they have it.
 Clients MAY limit the number of blocks and sidecars in the response.