Add warning for outdated docs

[pfitzseb]

Fixes #1449 (and #1302).

This obviously only works for newly generated docs. For already generated old documentation package authors can manually run a script like https://gist.github.com/pfitzseb/4b910449e21b51fed4b4a2a7c20912ff to add the necessary elements.

Oh, and because I was wondering about whether adding a noindex meta tag dynamically actually prevents Google from indexing the page: Yes, apparently it does.

Edit by @mortenpi: fix #1302 x-ref

[fredrikekre]

Oh, and because I was wondering about whether adding a noindex meta tag dynamically actually prevents Google from indexing the page: Yes, apparently it does.

#1302 (comment) :D ( so I guess it also fixes that issue).

[mortenpi]

The approach LGTM, just a few small nitpicks.

[mortenpi]

For already generated old documentation package authors can manually run a script like https://gist.github.com/pfitzseb/4b910449e21b51fed4b4a2a7c20912ff to add the necessary elements.

You wouldn't be willing to turn this into a function and put it into DocumenterTools by any chance?

[pfitzseb]

Ok, just pushed a commit that cleans up the JS/CSS side of this. The overlay is now rendered as an admonition and respects themes:

[pfitzseb]

Ok, this is good to go from my end. Review comments are addressed.

You wouldn't be willing to turn this into a function and put it into DocumenterTools by any chance?

That makes a lot of sense :) I totally forgot about that package.

[pfitzseb]

Ok, this should be good to go.

Note that I've referenced JuliaDocs/DocumenterTools.jl#51 in the docs, so that needs to be merged and tagged first, I think.

[mortenpi]

Sorry for the delay, but LGTM. Thanks a lot for iterating on this @pfitzseb!

[pfitzseb]

Alright, let's get this merged?

[mortenpi]

Thanks again @pfitzseb and @fredrikekre! And sorry it took a while to get merged -- I am a bit short on time right now.

@pfitzseb: I think it would be good to ANN this on Discourse, since sooner the people switch over to 0.27 the better for the ecosystem. Would you be willing to post something by any chance once we get 0.27 out? This is the only really major thing on master (that has been merged), so I don't think we need to advertise any of the other stuff that much.

[pfitzseb]

Sure, I can do that.