Fix auto-publishing

[Ms2ger]

https://webassembly.github.io/js-types/js-api/index.html is way out of date, probably because CI fails to push to the gh-pages branch:

+git push git@github.com:WebAssembly/js-types.git gh-pages
Warning: Permanently added the RSA host key for IP address '140.82.114.4' to the list of known hosts.
git@github.com: Permission denied (publickey).
fatal: Could not read from remote repository.
Please make sure you have the correct access rights
and the repository exists.

from https://travis-ci.com/github/WebAssembly/js-types/builds/203525388

[Ms2ger]

@rossberg

[rossberg]

@tschneidereit, who is the owner of this proposal these days.

[tlively]

If someone figures out how to fix this, it would be great to update the instructions at https://github.com/WebAssembly/proposals/blob/master/howto.md. I noticed that the publishing didn't work after I followed the instructions for the feature-detection repo, but I haven't had time to look into it yet.

[Ms2ger]

@tschneidereit will you have time to do this or can you give me access to do it?

[SPY]

Fixed