Add decoded:Legal's v3 onion service to NextGenOnions wiki

https://trac.torproject.org/projects/tor/wiki/doc/NextGenOnions

Please add decoded:Legal's v3 onion service:

http://dlegal66uj5u2dvcbrev7vv6fjtwnd4moqu7j6jnd42rmbypv3coigyd.onion/

For verification purpose: https://raw.githubusercontent.com/alecmuffett/onion-sites-that-dont-suck/master/README.md