draft-savage-ppm-3phm-mpc-01: section names 4.4 and 4.5 repeat

[tgeoghegan]

Sections 4.4 and 4.5 are titled "Distributed Zero-Knowledge Proofs" and "Distributed Zero Knowledge Proofs", respectively. Perhaps they should be merged into a single heading?

[martinthomson]

Fixed in a recent update.