Task: Update EigenPod Docs

[Sidu28]

Description

Update EigenPod docs to relfect the new capella->deneb switch in the EigenPodManager that turns on the deneb-specific proof path

Some context on the change:
As per deneb upgrade, an additional 2 fields are added to the ExecutionPayloadHeader container which means that it merkelizes differently (theres an extra layer to the tree), specifically the height of the merkleized ExecutionPayloadHeader is now 5 instead of 4. These two fields however are not connected to our proofs and do not change them. See the deneb updates here.

This PR adds a switch that allows us to set a deneb fork timestamp twice - once from 0 -> to type(uint64).max and then a second time type(uint64).max -> actual_deneb_fork_timestamp. That way, capella withdrawal proofs work along with deneb withdrawal proofs

Action Items

• Add doc edits
• Get review

Blocking Issues

n/a