Add a maintainer page, listing all packages maintained/owned by someone

[sylbru]

I often find it cumbersome to navigate to other packages. It might be made easier in a lot of cases by adding a “maintainer” page, listing all packages maintained/owned by someone. The username in the header would link to that page (“ianmackenzie”) in the screenshot below. It’s currently not a link, despite being style exactly the same as the package name and version.

As there is a page for the package listing all different versions, it would be much more consistant to also have a page for the package maintainer:

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Sorry @ianmackenzie for borrowing your username for this issue, but I happen to spend a lot of time in the docs of your libraries these past few days :) And a maintainer page would be especially useful in this case, as these libraries (elm-units, elm-3d-camera, elm-3d-scene, elm-geometry…) are quite interdependent.

[rlefevre]

Note that until it is supported in the official version, this feature is present in https://elm.dmy.fr/ (and https://dark.elm.dmy.fr/) alongside with a bunch of others improvements proposals (https://discourse.elm-lang.org/t/unofficial-mobile-friendly-package-website-exploration/5180).

[sylbru]

@rlefevre Looks great!