Request a custom option extension number for Wire

[Davidknp]

Project: Wire

Website: https://github.com/Davidknp/wire

We need one globally registered extension number for google.protobuf.FileOptions. The public option will be wire.v1.contract, a single message-valued extension containing Wire contract endpoint metadata.

[esrauchg]

Feel free can send a PR that adds yourself to the .md file of claimed Options extensions.