Replace "updated" with "modified" in Electra spec

[jtraglia]

This PR does the following:

• Replace usages of "updated" with "modified" to be consistent with previous specs.
• For modified functions, ensure there is a note about the changes.
  • I updated some of these notes to be consistent with other specs.
  • Some of these notes could be better 😅
• Delete notes for new functions as we don't normally do this.
  • This was for process_withdrawal_request and process_deposit_request.
• Replace "NOTE" with "Note" and "Electra:EIP-7251" with "Electra:EIP7251" for consistency.
• Fix some excess blank lines & missing blank line nits.

[mkalinin]

LGTM!

[ralexstokes]

great thanks!

[ralexstokes]

@jtraglia I tried to save you some work by fixing a rebase in the web UI but it looks like I messed something up w/ the TOC

if you can plz fix im happy to merge this in, may just want to drop my commit and handle the conflicts that way

[jtraglia]

if you can plz fix im happy to merge this in, may just want to drop my commit and handle the conflicts that way

No worries! It was a simple fix. I think we should be good now.