IRC notifications over SSL and unstandard ports are undocumented

[Mikaela]

Originally reported at travis-ci/travis-ci#5093

The documentation only talks about chat.freenode.net#channel syntax which doesn't say anything about SSL or alternative ports.

It should also have SSL and alternative port example visible somehow:

notifications:
  irc:
    - "irc://chat.freenode.net:8000/#plaintext_channel"
    - "ircs://chat.freenode.net:7070/#ssl_tls_channel"

[Mikaela]

And there was documentations instead of notifications in the title for a long time without anyone noticing/commenting it.

Edit: and apparently ports instead of ports.