Merge pull request #4056 from ralexstokes/electra/p2p-clarification-b…

…lob-count

clarify blob count validation on blob subnets

specs/electra/p2p-interface.md

@@ -14,6 +14,7 @@
       - [Global topics](#global-topics)
         - [`beacon_block`](#beacon_block)
         - [`beacon_aggregate_and_proof`](#beacon_aggregate_and_proof)
+        - [`blob_sidecar_{subnet_id}`](#blob_sidecar_subnet_id)
       - [Attestation subnets](#attestation-subnets)
         - [`beacon_attestation_{subnet_id}`](#beacon_attestation_subnet_id)
   - [The Req/Resp domain](#the-reqresp-domain)
@@ -77,6 +78,14 @@ The following validations are added:
 * [REJECT] `len(committee_indices) == 1`, where `committee_indices = get_committee_indices(aggregate)`.
 * [REJECT] `aggregate.data.index == 0`
 
+###### `blob_sidecar_{subnet_id}`
+
+*[Modified in Electra:EIP7691]*
+
+The existing validations all apply as given from previous forks, with the following exceptions:
+
+* Uses of `MAX_BLOBS_PER_BLOCK` in existing validations are replaced with `MAX_BLOBS_PER_BLOCK_ELECTRA`.
+
 ##### Attestation subnets
 
 ###### `beacon_attestation_{subnet_id}`