fix(ci): deploy path for book

[vados-cosmonic]

This commit fixes the deploy path (which changes slightly, due to mdbook-linkcheck)

[vados-cosmonic]

Hey @itowlson would you mind taking a look at this PR really quick -- it looks like adding mdbook-linkcheck changes the output directory just slightly (puts the output in /html) which breaks the deploy CI

[itowlson]

Fingers crossed, otherwise maybe we're best rolling it all back until we can test e2e?

[vados-cosmonic]

WHEW! Thank you @itowlson 🙇

I'm fairly certain this is the fix. I also added a clear test to make sure this doesn't happen again in the deploy CI step (i.e. I look for /index.html in the deploy dir) -- thanks for taking another look so late 🙇

[EDIT] Also once #226 is rebased and merged the builds both in PRs and for deploy should be dramatically faster.

[itowlson]

CI is still breaking, and I'm about to become busy for the evening. Maybe the safest thing to do is reset to a previous successful build, then take it step by step tomorrow, this time starting from your "run mdbook on PRs" PR?

[vados-cosmonic]

Ironically the bash check I inserted is what failed -- please feel free to go back to the previous build, we'll pick it up tomorrow

[itowlson]

I've merged the fix, fingers even crosseder than before!