[css-fonts-4] Restore monospace in generic family

[cdoublev]

Following 69f7f7a, I think <generic-complete> is missing monospace.

[svgeesus]

Thanks!

[cdoublev]

@svgeesus, I cannot see the change live. The spec build after the commit failed with Error: The operation was canceled.. There was a successful build from another commit (also for CSS Fonts 4) a few minutes later though. Do you know how to fix this problem?

[svgeesus]

Thanks for noticing! That is so odd. The commit shows up in the history but has a red x.

I have fixed it by re-applying that small change, but sure would like to know how it failed in the first place.

[cdoublev]

My mistake: I edited the commented (hidden) version of the production.

<!-- <pre class=prod>
    ...
    <dfn><<generic-complete>></dfn> = serif | sans-serif | system-ui | cursive | fantasy | math