Fix typos in the specification of the End-to-End Options header
Fix typos in the specification of the End-to-End Options header

- Use everywhere the same capitalization for "End-to-End"
- Update copy/paste leftovers from "Hop-by-Hop Options" header

Closes #4070

GitOrigin-RevId: 280f90d85bedc0350614f7a9fc8c58af90cb1554

netsec-ethz/scion,netsec-ethz/scion,netsec-ethz/scion,netsec-ethz/scion