Update libraries.html

[hoereth]

doesn't quite fit any existing category, so I created the "Google Static Map" category.

[googlebot]

Thanks for your pull request. It looks like this may be your first contribution to a Google open source project (if not, look below for help). Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

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[hoereth]

I just signed it!

[googlebot]

CLAs look good, thanks!