x/website: links in header/footer of tip.golang.org should redirect to pkgsite at tip

[ahmetb]

It seems that with the shift towards pkgsite (pkg.go.dev), now clicking on the https://tip.golang.org > "Packages" link does not make it possible to browse the stdlib packages in "tip" (since it just sends the user to the https://pkg.go.dev/ homepage, which has no indication of "tip" that the user can easily find.)

This wasn't always the case: http://web.archive.org/web/20190318200504/https://tip.golang.org/pkg/ In the past, clicking Packages from the navbar showed the visitor package documentation from the tip.

Proposal: clicking on Packages from the navbar on tip.golang.org should send the user to a page where they can browse the packages at the tip, such as https://pkg.go.dev/@master but that does not work, I think (although the @master suffix for the URL works if the rest of the URL is a valid package name).

[cherrymui]

cc @dmitshur @rsc

[dmitshur]

This was done in other cases, for example https://tip.golang.org/pkg redirects to https://pkg.go.dev/std@master. Looks like this is an edge case that was missed, and just needs to be fixed. Thanks for reporting.