Explicitly define updated light-client containers for Capella

specs/capella/light-client/sync-protocol.md

@@ -51,6 +51,21 @@ class LightClientHeader(Container):
     execution_branch: ExecutionBranch
 ```
 
+### Modified `LightClientUpdate`
+
+```python
+class LightClientUpdate(Container):
+    # [Modified in Capella] References the Capella-specific LightClientHeader
+    attested_header: LightClientHeader
+    next_sync_committee: SyncCommittee
+    next_sync_committee_branch: NextSyncCommitteeBranch
+    # [Modified in Capella] References the Capella-specific LightClientHeader
+    finalized_header: LightClientHeader
+    finality_branch: FinalityBranch
+    sync_aggregate: SyncAggregate
+    signature_slot: Slot
+```
+
 ## Helper functions
 
 ### `get_lc_execution_root`

specs/deneb/light-client/sync-protocol.md

@@ -22,6 +22,23 @@ Additional documents describes the impact of the upgrade on certain roles:
 - [Full node](./full-node.md)
 - [Networking](./p2p-interface.md)
 
+## Containers
+
+### Modified `LightClientUpdate`
+
+```python
+class LightClientUpdate(Container):
+    # [Modified in Deneb] References the Deneb-specific LightClientHeader
+    attested_header: LightClientHeader
+    next_sync_committee: SyncCommittee
+    next_sync_committee_branch: NextSyncCommitteeBranch
+    # [Modified in Deneb] References the Deneb-specific LightClientHeader
+    finalized_header: LightClientHeader
+    finality_branch: FinalityBranch
+    sync_aggregate: SyncAggregate
+    signature_slot: Slot
+```
+
 ## Helper functions
 
 ### Modified `get_lc_execution_root`

specs/electra/light-client/sync-protocol.md

@@ -57,6 +57,23 @@ Existing `GeneralizedIndex` constants are frozen at their
 | `CURRENT_SYNC_COMMITTEE_GINDEX_ELECTRA` | `get_generalized_index(BeaconState, 'current_sync_committee')` (= 86)        |
 | `NEXT_SYNC_COMMITTEE_GINDEX_ELECTRA`    | `get_generalized_index(BeaconState, 'next_sync_committee')` (= 87)           |
 
+## Containers
+
+### Modified `LightClientUpdate`
+
+```python
+class LightClientUpdate(Container):
+    # [Modified in Electra] References the Electra-specific LightClientHeader
+    attested_header: LightClientHeader
+    next_sync_committee: SyncCommittee
+    next_sync_committee_branch: NextSyncCommitteeBranch
+    # [Modified in Electra] References the Electra-specific LightClientHeader
+    finalized_header: LightClientHeader
+    finality_branch: FinalityBranch
+    sync_aggregate: SyncAggregate
+    signature_slot: Slot
+```
+
 ## Helper functions
 
 ### Modified `finalized_root_gindex_at_slot`