Add "Powered by ..." message to footer

[pfitzseb]

This should help a bit with SEO and therefore Julia's ranking (both for Julia itself and packages). AFAIU it's not ideal to put this in the footer, but I don't know enough about how Google ranks websites to figure out something better.

Open questions:

• Is everyone happy with this?
• Should there be an opt-out mechanism?
• Should this be an opt-in feature (would completely defeat the purpose though, I think)?
• Is the styling ok?

cc @ViralBShah

Edit by @mortenpi: fixes #1184

[KristofferC]

I think it looks nice. Adding "Julia" to the page also makes it more likely to be found when googling something related to the package + "julia". Right now, there are many documentation pages without the term "julia" at all which might lead to worse discoverability.

[johnnychen94]

Literate.jl also adds this to the footer, so an opt-out mechanism would be a must from my perspective. See the credit keyword in the Literate docs.

With an opt-out mechanism, users could manually customize credit to two or more packages in one line.

[ViralBShah]

I think we should have this as the default message but easy to change.

[mortenpi]

Looks good, thanks for tackling this @pfitzseb!

1. As we said in A customizable footer on generated pages #1184, with this phrasing, I think it makes sense to have it be opt-out. I see it as a way to subtly advertise Documenter & Julia to the readers, with any SEO benefits being incidental. I do think there should be an option to opt-out. A footer keyword to HTML?

2. I think ideally we'd also allow the users to override the content. Probably formatted as an (inline) Markdown string, so that e.g. links would also work?

3. Finally, maybe it would be also good to allow it to be overridden on a per-page basis in an at-meta block? This would allow tools like Literate to put their "Powered by" messages into the footers (cc @fredrikekre).

The latter two could definitely be done later as follow-ups.

[pfitzseb]

Alright, added a footer argument to HTML that defaults to "Powered by [Documenter.jl](https://github.com/JuliaDocs/Documenter.jl) and the [Julia Programming Language](https://julialang.org/).". Can be set to the empty string to hide the footer completely (could also allow nothing here, I suppose).

The argument checking for footer is very rudimentary at the moment, so in theory you could set a header or whatever. I can add an early check for that if necessary.

[mortenpi]

The argument checking for footer is very rudimentary at the moment, so in theory you could set a header or whatever. I can add an early check for that if necessary.

What might work is to see if it parses to a single Markdown.Paragraph?

[pfitzseb]

Done :)

[mortenpi]

I took the liberty of adding the CHANGELOG and try it out in test/examples. I think only thing left is adding docs about the footer keyword into the docstring of HTML?

[pfitzseb]

Alright, pushed an update to the docs.

[johnnychen94]

Customized footer affects globally. Using this with Literate.jl would either 1) inserting two credit footers for Literate-generated pages, or 2) add credit for Literate even in other pages that are not Literate-generated.

[mortenpi]

LGTM, thanks again @pfitzseb!

Customized footer affects globally. Using this with Literate.jl would either 1) inserting two credit footers for Literate-generated pages, or 2) add credit for Literate even in other pages that are not Literate-generated.

Yeah, it might be nice to be able to override it also on a per-page basis: #1370.