Update payload_attributes example (#550)

Co-authored-by: Paul Harris <[email protected]>

Author: ensi321

apis/eventstream/index.yaml

@@ -147,7 +147,7 @@ get:
                 ignored by block builders and most other API consumers.
               value: |
                 event: payload_attributes
-                data: {"version": "capella", "data": {"proposer_index": "123", "proposal_slot": "10", "parent_block_number": "9", "parent_block_root": "0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884560367e8208d920f2", "parent_block_hash": "0x9a2fefd2fdb57f74993c7780ea5b9030d2897b615b89f808011ca5aebed54eaf", "payload_attributes": {"timestamp": "123456", "prev_randao": "0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884560367e8208d920f2", "suggested_fee_recipient": "0x0000000000000000000000000000000000000000", "withdrawals": [{"index": "5", "validator_index": "10", "address": "0x0000000000000000000000000000000000000000", "amount": "15640"}]}}}
+                data: {"version": "electra", "data": {"proposer_index": "123", "proposal_slot": "10", "parent_block_number": "9", "parent_block_root": "0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884560367e8208d920f2", "parent_block_hash": "0x9a2fefd2fdb57f74993c7780ea5b9030d2897b615b89f808011ca5aebed54eaf", "payload_attributes": {"timestamp": "123456", "prev_randao": "0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884560367e8208d920f2", "suggested_fee_recipient": "0x0000000000000000000000000000000000000000", "withdrawals": [{"index": "5", "validator_index": "10", "address": "0x0000000000000000000000000000000000000000", "amount": "15640"}], "parent_beacon_block_root": "0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884560367e8208d920f2"}}}
             blob_sidecar:
               description: The node has received a BlobSidecar (from P2P or API) that passes all gossip validations on the blob_sidecar_{subnet_id} topic
               value: |