Show link to docs on a build

[stsewd]

This PR is related to readthedocs/ext-theme#278 and #2469

For now, I trying to solve this:

If we're on a build, use the build version for the view docs link! This gets me every time

I think the View Docs button must remain the same on all the project area, otherwise it would be confusing.

I don't know much css, so any feedback is more than welcome :).

Here is how it looks right now

And how it will looks like after merging

This is still very WIP, so any feedback and suggestion is welcome!

[stsewd]

I don't know how to do this on a better way, what js library are you using?

[ericholscher]

Knockout I believe.

[stsewd]

Hope I didn't break any other parts with the css change.

[ericholscher]

Looks good to me in local testing. Will let @agjohnson comment on the HTML/JS stuff.

[ericholscher]

Knockout I believe.

[humitos]

This is a very personal opinion and so probably not that relevant

I think that with this change we are loosing some visual strengh impact on the status of the build when changing the red/green square by colorizing just the text Build readthedocs/readthedocs.org#111 with red/green.

I'd like to have the link view docs next to the old green square, instead of changing the structure.

Something like this:

[agjohnson]

Visually, I prefer the change that @humitos suggests as well.

Alternatively, the view docs link would also fit in the right float area nicely. My vote would be for adding the link to this section.

My original thought is that we'd repurpose the main View Docs button, as it is really confusing that it always points to the same branch. This is another option.

[agjohnson]

From the technical side, these changes looks good 👍

The changes to revert the styling to the old UI will likely revert a lot of these additions however.

[stsewd]

I reverted the other changes and put the link to the right as @agjohnson suggest

On building state

No staff user

Staff user

[humitos]

I like this new proposal!